Adele Adkins is an anomaly. She has won at the fame game simply by refusing to play it, and her music is all the better for it. She’s perhaps the most important British singer of right here, right now. In her first interview in forever, Adele talks about being a mum, her fear of fame and why she wouldn’t want to follow up 21, even if she could.

When she was ten-years-old, Adele's granddad died. She was devastated. "I loved him so much, more than the world." As well as her own grief, she sensed the depth of loss felt by her grandmother. "My grampy and my nana had always been my ideal relationship - ideal friendship, companionship, everything. Even though I'm sure there's loads of shit I don't know about, as their granddaughter it was bliss, just heaven. I was so, so sad." So acute was the grief that she decided there and then to become a heart surgeon. "I wanted to fix people's hearts," she says. A year later, Adele started senior school and threw herself into biology lessons at Balham's Chestnut Grove School. Until she discovered, well, "fun - and boys. I gave up on it. My heart wasn't in it anymore." And that was that for Adele's aortic ambitions.

A decade after the death of her gramps, Adele returned home to London from LA where she had been recording with the producer Dan Wilson for the follow-up to her debut album, 19. She got off the 11-hour flight, jetlagged off her face, and went over to her mum's house. "I played her the unmixed version of Someone Like You," she remembers. "She was pretty teary. 'You are a surgeon,' she said, 'You're fixing people's hearts.'" She pauses and shrugs. "It's all a bit Sliding Doors really, innit?"

The tropes of Gwyneth Paltrow's 1998 what if comedy-drama are something of a theme found on Adele's new album, 25. When she was ready to start work on the record, Adele walked down to the local shop ("I do actually walk," she says, laughing) and bought herself a brand new notebook. "I do it every album. I buy a new pad, sniff it - 'cause smell is important - and then I get a big, fat sharpie and write my age on the front page. 25 has five exclamation marks after it 'cause I was like, 'How the fuck did that happen?!' 21 to 25." The record is about getting older and becoming nostalgic, she says. It's about what was, what is, what might have been. It's about missing things that you had no idea were so precious, like being 18-years-old and drinking two litre bottles of cider in Brockwell Park with your mates. "Those were the most real and best moments of my life and I wish I'd known that I wasn't going to be able to sit in the park and drink a bottle of cider again." Not because she's famous, but because her life - and the lives of her school friends - has moved on. No one is a teenager anymore. "I think the album is about trying to clear out the past," she says slowly. "Becoming a parent and moving past my mid-twenties, I simply don't have the capacity to worry about as many things that I used to really enjoy worrying about." She loved worrying? "Oh yeah, I used to fucking love the drama of all of it," she hoots, "but now I'm a mum I only have so much head space. I've got to clear a lot of stuff the fuck out, which is really therapeutic, 'cause I can really hold a grudge. Life is so much easier when you don't hoard your past."

25 will possibly be interpreted by critics as a rumination on fame and fortune, but that doesn't seem either accurate, or fair. As with her past records, Adele perfectly translates individual experience into collective feeling. She does this with her voice, but also with her songwriting, which is powerfully simple but oh so evocative. Her heart gets broken because our hearts get broken. She struggles, we struggle, regardless of who we are and what we do. 25 reflects on how we change, hugely, in our twenties whether we're a world famous singer or a graduate or a plumber or a new mum.

Whatever 25 is - and you get the impression that Adele is still figuring that out as the record is being mixed and mastered - it isn't 21, the 30-million selling multi-award winning album that catapulted her from critical success to global superstar. "I was very conscious not to make 21 again. I definitely wasn't going to write a heartbreak record 'cause I'm not heartbroken, but I probably won't be able to better the one I did, so what's the point? Bit cliché, innit?" she says. "Also, how I felt when I wrote 21, it ain't worth feeling like that again." How did she feel? "I was very sad and very lonely. Regardless of being a mum or a girlfriend, I didn't want to feel like that again," she reiterates.

Adele Laurie Blue Adkins, now 27-years-old and with an MBE no less, appears for her first interview in three years through the - appropriately enough - sliding doors of the artist lounge at the London offices of her record label, XL, home also to Dizzee, M.I.A., and Tyler, The Creator, who has hung out with Adele, and in 2014 described her to i-D as "a bowl of yellow and happiness." She's weighed down with headphones, a Macbook Pro, an XL promo bomber jacket, an iPhone 6 and a Bob The Builder bag. She asks for a green tea; "I'm trying to be healthy," she mutters before laughing that you can kind of kid yourself you've been for a Chinese if you drink green tea. "Reminds me of the taste of wontons," she says.

Dressed in black leggings, black vest, black cardi, black Nike 5.0+ Shields, nails bare, no jewellery, just two big hooped earrings, Adele plonks herself unceremoniously on the floor and prepares to play i-D seven songs from 25. "I'm nervous," she says, shooting a look with those luminous green eyes as she fiddles with the AV cable. "You're the first person to hear it outside of my manager." She scrolls through her iTunes. "Right, fuck, okay, what shall I play first? Okay, this one's called Hello and it's the first single." It's the track that semi broke the internet when XL previewed it during an X-Factor ad-break two weeks ago. She presses play and we're off. Hearing Adele's voice again after four years is really quite wonderful. Among the recently brilliant pop offerings of Taylor and Rihanna and Miley, Adele's vocal has been glaringly absent. Three and a half minutes later the song ends and we both have tears in our eyes. Well, I do.

She shot the video in Toronto in early October with the Cannes Jury Prize winning filmmaker and actor Xavier Dolan. He made her act, which she unexpectedly loved. "He said I was quite good. I had to cry and everything. You know what, I feel like a bit of a cunt after saying for all these years I'd never act, because I really enjoyed it." She had to leave her then two-year-old son, Angelo , at home, which wasn't so fun. "It was the most exhausting thing ever, being without my baby." How's life as a mum? "It's fucking hard. I thought it would be easy. 'Everyone fucking does it, how hard can it be?' Ohhhhh..." she sighs dramatically, "I had no idea. It is hard but it's phenomenal. It's the greatest thing I ever did. He makes me be a dickhead, and he makes me feel young and there's nothing more grounding than a kid kicking off and refusing to do what you're asking of them. It used to be that my own world revolved around me, but now it has to revolve around him." Adele's upbringing is presumably markedly different to that of her son. Brought up alone in Tottenham by her mum, Penny, who would sneak her into Brixton Academy when she was three-years-old to watch the Beautiful South and the Cure, Adele came from your average working-class background. "I had a great childhood. I was very loved, which I realise now is so important, being a mum. The way I was brought up, the morals are the same, but the environment is very different to how I'm raising my child. It was fun and it's worlds away from what I do now and I'm very conscious of that."

In a similar way to Someone Like You, Hello, which is produced by Greg Kurstin, feels like "a moment". It makes your heart rise and fall and rise again. "The song is about hurting someone's feelings but it's also about trying to stay in touch with myself, which sometimes can be a little bit hard to do," she explains. "It's about a yearning for the other side of me. When I'm away, I really, really miss my life at home. The way that I feel when I'm not in England, is..." she pauses, "desperation. I can't breathe anywhere else." Why? "I dunno. I'm so attached to my whole life here. I get worked up that I'm missing out on things. So Hello is about wanting to be at home and wanting to reach out to everyone I've ever hurt - including myself - and apologise for it."

It struck me initially that it might be about an apology of sorts to the guy she used to date, the one Someone Like Youis about. "Oh, god no," she says immediately. "That's over and done with, thank fuck. That's been over and done with for fucking years. No, it's not about anyone specifically. It's about friends, ex-boyfriends, it's about myself, it's about my family. It's also about my fans as well. I feel like everyone thinks I'm so far away and I'm not. Everyone thinks I live in fucking America, I don't." She has that British working-class mentality that all British working class people share - we hate the idea that anyone would ever think we've sold out, forgotten our roots. "Sometimes I think people worry about chatting to me, that I've changed. But I like to think I haven't. I don't feel like I have."

She plays eight tracks in total. Rolling In The Deep producer Paul Epworth pops up on the ghostly hymn of I Miss You. Adele nods along, eyes tight shut. It's about sex, right? She breaks out another huge laugh. "It's about intimacy on every level. It's about sex, it's about arguing, one of the most intimate moments in my life. 'Cause you just blurt it out. It's a bit like, a drunk tongue is an honest one. That's definitely my motto, in life. That's why I don't really like drinking no more. The panic you get when you wake up the next morning." Even Adele gets The Fear.

When We Were Young could be the album's Rolling In The Deep. A great big fat love song, it's a 70s styled shimmery disco ballad produced by Ariel Rechtshaid and co-written with Tobias Jesso Jr., an unknown (until Adele tweeted about him to her 23.4m followers) who she discovered after hearing his song Hollywood. She flew to LA and recorded it on Philip Glass's piano, as you do, at Tobias's friend's nan's house in Brentwood. "It used to be this mad party house and for some reason his piano was there so we wrote the song on that."

A Million Years Ago, produced again by Kurstin channels Celia Cruz's Tito Puente years and puts more tears in our eyes. Well, my eyes. I miss the air/ I miss my friends/ I miss my mother/ I miss it when life was a party to be thrown /but that was a million years ago. "Do you really like that one?" she says looking genuinely surprised. "That only went on the record three days ago, right at the last minute. It's very stripped-back, it's very 19. It's just me on guitar." She decides to play one more track. "Do you want to hear the Danger Mouse one or the Bruno Mars one?" It's an impossible decision, so she makes it for me and plays both. River Lea is a Hometown 3.0 of sorts. 'When I grew up as a child I grew up on the River Lea/ Now there's some of that water in me. To wit: I'll never change. Tottenham is my mind, body and soul.' The Bruno Mars one is all sorts of everything. 'We was gonna make something cool, but then we were having too much fun.' It throws every piece of Barbara Streisand, Bette Midler diva shtick at the wall to immense, overwhelming effect. It even has a key change. It's brilliantly ridiculous. "I've never sung so hard in me whole life. Can you imagine the fun me and Bruno had making that?" Yes, frankly.

Unlike her first two albums, which had distinct soul, R&B and bluegrass overtures, 25 feels firmly centred in contemporary pop although there are some very decisive nods to the 70s — The Carpenters, Aretha, Carly Simon and Stevie Nicks, who she met recently at Fleetwood Mac's 02 show. She takes great joy in reenacting their encounter. "I was sobbing all over her oh my god. I don't really like crying in front of famous people because it's awkward and it can make them feel really uncomfortable. But I couldn't contain myself."

Much has been made of the time it's taken to record 25. But Adele wouldn't - couldn't - be rushed. "Sometimes I wonder if I've missed it by a year, bringing it back. But you know, I was being a mum. I couldn't rush it. And you've got to give people a chance to miss you." She tried to get back into the studio in 2013, going to her friend Kid Harpoon's studio to try out some stuff. "Just for a laugh. It was a 'dip my toe back in the water' thing really. Me and Tom get on great, so I went in with him 'cause I knew there was no pressure. We just chatted, mainly, and got chocolate tempura. I don't know why I wasn't ready, I just couldn't access myself."

Things didn't fall into place a few months later either, when she went to New York to work with Ryan Tedder, the OneRepublic frontman with whom she'd made Turning Tables and Rumour Has It. What did come out of their time in New York was the song Remedy, about her best friend and her grandparents and her boyfriend, but mostly about her son, who she had with Simon Konecki (they're still very much together FYI, despite the tittle-tattle of the tabloids and Sidebar of Shame speculation). "Because Remedy is so great, and I loved singing it so much I got excited like 'I'm on a roll!' I weren't on a roll," she deadpans. "So I started knocking out some shit songs - they weren't shit," she corrects herself, "they were good pop songs, but I was just trying to bang it out, I didn't want to think about it. And, you know, it got rejected. My manager was like, 'This isn't good enough.'" Ouch. "Yeah, it knocked my confidence a bit, but I also knew, you know. And then I flew Rick Rubin over, to play him the songs and he was like, 'I don't believe you.' That's my worst fear: people not believing me. So I went back to the drawing board."

One day she and Tedder were having lunch and Taylor Swift's Trouble came on the radio. "I was like, 'I love this song, who did this?' and he's like 'Max,' and I'm like, 'Oo's Max?' and he's like 'Max Martin!' and I'm like, 'Oo's Max Martin?'" The world's number one songwriter, she discovered after Tedder sent her a YouTube clip of his work. The song provides another 'moment' for 25. Send My Love To Your New Lover is a bit like Martin's Can't Feel My Face for the Weeknd - totally unexpected. It has a bit of a calypso vibe ("It's a bit of fun, innit? You ain't got to be dark all the time") and an amazing opening line: This was all you/ none of it me. "I love it, it's fucking sick," she says. "Straight away, a million people in my life will be like, 'Oh shit, what have I done...'"

She wrote the skeleton of the song when she was 13. After deciding not to be a heart surgeon after all because "boys", inspiration for her current career arrived in 2008 when Amy Winehouse released Frank. Adele immediately grabbed the guitar and began writing. "If it wasn't for Amy and Frank, one hundred per cent I wouldn't have picked up a guitar, I wouldn't have written Daydreamer or Hometown and I wrote Someone Like You on the guitar too. Contrary to reports, me and Amy didn't really know each other, we weren't friends or anything like that. I went to Brit School and she went for a little while. But a million per cent if I hadn't heard Frank this wouldn't have happened. I adored her."

Talk turns to the recent documentary, Amy. "I did see it, yeah," she says. "I wasn't going to. I loved her and I went through my own massive grieving process as her fan. I'd finally got to a place where I felt really great about the impact she'd had on my life, in every way. I felt really, really fond of it all. But then I read this review of it and that made me go and see it." So what did she think? "I got super emotional with the funeral footage. But I wasn't really that into the saved voicemails and stuff like that," she frowns. "I felt like I was intruding so I actually felt a little bit uncomfortable and that ruined it for me. I love watching her, but I kind of wish I hadn't seen it. But you know, I love Amy. I always have, I always will. Do you know what makes me super sad? That I'm never going to hear her voice again, other than how I've heard it." We both have tears in our eyes. Well, I do. The parallels between Amy and Adele can't be ignored. North London girls with absent dads who loved their Ellas and Ettas and who thought they'd release an album or two and maybe make the pages of Mojo and carry on with their lives. That's not how it worked out for either of them, and you can tell it genuinely shocked them both. But it's their differences that are key; it's why Adele is still here and, perhaps, why Amy is not.

This is the third time, for a third album, that I've interviewed Adele. The first time was in 2008, the second in 2011. Each time she's been brilliant company: absolutely hilarious, engaged, present, interested, incredibly sharp and unfailingly honest. In the past she'd taken great pleasure in affectionately taking the piss out of pop stars - never mean, always funny - in much the same manner Winehouse managed to cut with charm. She's perhaps a little more cautious now than she was. She is still wildly, brilliantly inappropriate, thank god. "I gave birth a few nights before the Skyfall premiere, that's why I didn't do anything for it. He was about to drop out my fanny at, like, any moment."

Adele stuffs a lot into a 90-minute conversation, chattering at a rapid rate. She's not on Facebook and doesn't do Netflix or podcasts, but she's obsessed with MTV's Teen Mom, the Walking Dead and American Horror Story. She doesn't sing much at home other than Row Row Row Your Boat, except the odd Alison Krauss song and then her son moans, she laughs. She says her highlights of the 21 years, aside from the awards and accolades were things like passing her driving test first time. ("I still can't believe I can drive actually"). She cried "all the time" whenSomeone Like You went to number one, her first ever, and remembers her show-stopping Brits performance proudly. "I never thought it would change my life the way it did. I'd been shitting myself about standing on that fucking B-stage on my fucking own, belting it out. I thought everyone was gonna boo me off." She talks about doing the Globes and how drunk they, "the Hollywood lot", got and then when she was coming offstage she reached for someone's hand and it turned out to be "George-Fucking-Clooney's". She talks about making the video for Helloand Xavier asking her to cry, so she made them play Labrinth's Jealous. "The minute that piano starts I'm like," she breaks into a fake wail. "Snot going everywhere. I can't cope with that song. You could play it at my kid's birthday and I'd burst into tears." She's camp as Christmas; she displays her Oscar in homage to the way Barbra Streisand displays hers. "I've got my red carpet dress, the Oscar and the envelope in the cabinet, next to my 'Best Mummy' award!" Brits, Grammy's and an Oscar… 2011 must have been mental. "Can you imagine!" All this is still a surprise, she insists. "After someone from XL heard her on MySpace in 2007 and asked her to come in for a meeting, she thought they were going to ask her to be a scout. "I never saw any of it coming. I didn't realise it was going to get so carried with itself."

She seems reluctant for conversation to stray too far into particular areas of her private life - she doesn't once mention her son or boyfriend by name. The subject of her dad, to whom she has been estranged for years, comes up only when she's talking about her granddad. She describes him not as "my dad's dad" but pauses and says "not my mum's dad". She was nervous about this interview, she admits. "When you're doing interviews for three years on the trot you know roughly what you're going to say and pretty much every question has been asked. So I was just nervous because I get worried that the question will be, 'Why don't you like being famous?' and it's not that." Does she dislike fame? "I'm just frightened of it, you know? Frightened of it destroying me and it ruining me, and me getting lost and turning into some of the people that I love with my whole musical heart. I get frightened. And I get frightened for the people that I love, feeling like they've lost me." She realises that she's perhaps coming across a bit serious, a bit heavy. "It's basically a bit like Stars In Their Eyes when you go into the smoke and you come out as someone else," she lets loose another tumultuous laugh. "I get worried of them looking at me going into the smoke and never coming out. It's a bit toxic, fame. I've got enough toxins in me body, I don't need any of that!"

It's incredible, unheard of really, for an artist in 2015 to be so famous and yet play the game as little as Adele does. Consider the hours, days, months Kim and Co. must spend online to upkeep Brand Kardashian. Even the Ellie Gouldings of this world are constantly on Twitter, ensuring fans are able to engage in the inane minutiae of their everyday existence. Adele rarely tweets, has only just joined Instagram, and has been papped perhaps three times this year, max. How on earth does she evade it all? "It's definitely harder to avoid it than it is to give into it. I think most people tend to give into it because it is easier, but I just can't. I'm uncomfortable with giving into that kind of thing. Me being photographed in Waitrose is being famous for no reason and that is something that I am not up for and I will not stand for, for myself." She avoids pap hot-spots like Bond Street and Soho. "It's not me trying to be like fucking anti-famous cunt-y, I just want to have a real life so I can write records. No one wants to listen to a record from someone that's lost touch with reality. So I live a low-key life for my fans."

This is why Adele is important. Not because she sells millions of records and wins every award going. She's important to me and to you because she sings about life in a way that deeply moves and affects us and she does this in spite of "engagement" and "coverage" and "reach". She doesn't play the fame game. She doesn't return with a new look or a new concept every album. Adele is an artist, not an entertainer. She's this generation's Patsy Cline and Stevie Nicks and Frank Sinatra and Aretha Franklin. She makes important records that spark the collective consciousness and sings songs that matter. She writes them herself, in her own time, and when they're ready she releases an album and does a handful of interviews.

Will 25 be as big as 21? Who cares? There will be a 29 and a 42 and, let's hope, an 89. Adele is a lifetime artist; whether her next album goes platinum or dust, there will always be more, she'll just keep singing. And (hopefully) she'll remain as honest and open. And therein lies her power. "I feel quite emotional actually, finishing my first interview in a long time, especially as it's with i-D, which I've cherished for years. Standing on the West Norwood fucking overground platform reading it with me parachute trousers on and all that." She seems happy and relaxed and more than a little relieved, both right now and generally in life. "For a while, it felt like this moment was never gonna come 'cause I couldn't access myself to write a record. So I'm super chuffed and really proud of the songs. I'm shitting myself about it all, but it will be exciting." What's next? "I'd like to tour properly. I'd like to see Britney in Vegas. Dunno about more kids. Maybe after what Xavier said, I'll go into acting… I'd like to make another record," she decides with a sense of finality. "I'd like to be able to stand the test of time and the speed that the world is moving. I'd like to make records forever with the time I've been given for this one. If I can do that I'll be really fucking happy." We both have tears in our eyes.