Jo Whiley interview: Whiley fox

"She looks exactly like Coco did when she was born – all that lovely thick hair," remarks Whiley, whose fourth child, her second daughter, is just seven months old and whom she hasn't seen for more than 24 hours since she's just come off air after her morning show.

Last night, her husband, music industry executive Steve Morton, to whom she's been happily married for 18 years, treated her to an overnight stay at London's hip Soho Hotel, the first time they'd had a romantic evening alone together for many months.

"It was bliss, but I'm dying to get home to give Coco a cuddle," says the DJ who has five million listeners and who is known for her ability to spot the music industry's next big thing. She regularly tops the polls for the sexiest voice on radio and has everyone on her speed dial from Bono to Chris Martin from Coldplay, who once stopped a gig to sing Happy Birthday to her down the phone and who has been known to babysit for Whiley at Glastonbury.

She has a wealth of such celebrity stories, although she's down-to-earth enough never to claim she's "a friend of the stars".

Nonetheless, her "good mate" Bono has been known to get down on his knees to tell her he adores her. Madonna spent three impromptu hours on her show and asked Whiley to present her award when she was inducted into the UK Music Hall of Fame. Liam and Noel Gallagher think she's one of the "coolest" women of their vast female acquaintance. When I mention this to Whiley, she laughs and exclaims: "Yeah, but you can never be cool to your kids!"

Such is Whiley's clout in the business that Brandon Flowers of The Killers was photographed with Coco Lux Francesca at her first gig when she was only days old, while Scissor Sisters sent the new-born an outfit, emblazoned with teeny skull-and-crossbones, a child's hot-pink electric guitar, and a CD of rock anthems chosen especially for babies.

"The coolest present she received," says Whiley, who reportedly earns 250,000 a year from the BBC, in addition to fronting television coverage of the mudbath that is the Glastonbury Festival.

To prove her point about Coco's abundant hair, when the proud young parents have left the coffee shop, we look at a photograph of "the Whiley-Morton tribe" – as she and her husband have christened their brood – in Whiley's enormous bed together shortly after Coco was born. With Coco, who is fast asleep, are her brothers Jude (ten), Cass (eight) and 17-year-old sister India, who stares warily into her mother's camera lens.

"I think she was still shell-shocked," admits 43-year-old Whiley. It is hardly surprising that India looks slightly spaced out since she and her mum were watching Heroes on TV – Steve was in Brighton at a gig with one of the bands he manages – when Whiley announced: "I think the baby's coming."

Her daughter was amazing, she recalls. "Totally calm and businesslike." India timed the contractions and when she'd ascertained they were five minutes apart she decided they needed to get to the hospital. She called her granddad – Jo's father, Martin, the family "manny" – and a close neighbour since they live in "a tiny village in the middle of nowhere", in Northamptonshire. Steve made it to the hospital by 1am and until then India did all the work, holding her mother's hand and talking to her.

When Steve arrived he asked India if she wanted to go home and she said no, she didn't. She stayed with her mother right through, offering encouragement.

"All I can remember is her there, eyes as big as dinner plates, leaving the room now and then, but totally involved," says Whiley, who has written a memoir, My World in Motion, about her life and career and what it feels like to be "almost famous". She is, after all, one of the few women to have stormed the bastion of the boys' club that is the rock business.

The title comes from the New Order song music executive Steve was plugging when he and Whiley first talked. "When I hear this track it takes me back to our first summer of love, a hedonistic whirl of love, football, champagne and music," she says. The song also sums up her life now: "A moving kaleidoscope of motherhood, family, work, relationship; a set of disparate shards twisting together to make a beautiful chaotic whole," she writes.

Most days, she claims, she's no yummy mummy. Indeed, she juggles ten things at once and "b*ggers up" every one of them. For instance, she gets a train every day from Milton Keynes to Euston and back, and has been known to leave, variously, her phone, changes of clothes, people's presents and the week's shopping behind. "Never a child. Yet."

At the time of Coco's birth, India was doing an A-level in photography – she's recently applied to Edinburgh College of Art. "So far away from home! I don't want to lose my baby even if she is on the threshold of adulthood," Whiley sighs with feeling when we meet at Broadcasting House.

We walk around looking for a quiet place to talk and have coffee. Slender and bare-legged, she's dressed in boho layers of white, grey and lavender-blue. On her feet she has colourful gladiator sandals from Aldo that she saw Beyonc wearing recently and just had to have.

As we wander around Portland Place, Whiley inevitably attracts the attention of a gang of workmen on a building site. She may be a mother of four, but like Shakespeare's Beatrice she's still worth the whistle. She insists, though, that there's only one photograph in her book of which she can honestly say: "Why can't I look like that every day?" (It was for a shoot for Glamour magazine and she looks absolutely fabulous in it.)

Meanwhile, she's become a favourite subject for her daughter. India had already taken a series of photographs of her when she was about nine months pregnant – "amazing, intense shots of me wearing a bra and knickers with very extreme make-up based on Courtney Love and with words like 'EXIT' painted on my belly, with an arrow pointing downwards. God knows what her photography teacher made of them," Whiley admits. "Parents' evening was interesting after she'd handed them in, I can tell you."

India has followed up that project with pictures of her mother giving birth. "We have an amazing shot she took of me, screaming my head off as Coco came out..." It was a precious time, says Whiley.

Sometimes, though, she admits over the lattes, she's wondered if they did the right thing letting India stay for the birth. "I'm so proud of her and so grateful to her for being there with me. But Steve and I did worry that we had traumatised her.

"For the first 24 hours or so she had that extraordinary look in her eyes women have after they've given birth: primal, intense.

"And she did announce that she was never doing that herself. So I think it's probably the best contraceptive ever. Now, I just think we have this wonderful thing we went through together – she knew on the same day that I did that I was pregnant – she found my pregnancy test which I'd stuffed into a coat pocket as I didn't want my dad to find it – and she was with me right through until the moment Coco was born."

Family is everything to Whiley, who is Northampton born and bred. Her "sunny-natured" dad, Martin, was an electrician working on building sites until he retired, while her mum, Christine – "the bravest and most honest person I know and a real beauty" – did odd jobs to make ends meet. "We didn't have much money, but Mum and Dad always nurtured me, kept me grounded, made me the person I am."

And then there's her sister Frances, who "has meant so much to us".

"Frances," says Whiley softly, "is different from most people and the difficulties Mum and Dad – and I – have experienced because of that difference have shaped all our lives and made us who we are, as individuals and as a family."

Frances, who didn't speak until she was ten, suffers from Cri du Chat syndrome, which is characterised in babies by a mewling, cat's cry, hence its name. Despite this Frances is gregarious, has many friends and interests, and is mad about music, like the entire Whiley clan, who are all evangelical about it. Now, Frances performs as a DJ at events for Mencap. "People love her," says Whiley, who hits that speed dial every year to lure the likes of U2, Razorlight and Duffy to play at a huge charity gig she organises.

"We really got into pop very young because Dad has a great ear for a hit record and still spots the potential in so many bands way before they achieve success. Long before Elbow got their Brit and Mercury awards my Dad was telling anyone who'd listen how brilliant they were. Same with Kasabian, Dido – too many to mention," she says.

Although Frances has a complex character, she will never live by herself, never work, never have an adult relationship, never drive a car, never have children, Whiley reveals in My World in Motion. "She will for ever remain a child and so my parents' responsibilities to her – and mine, to a certain extent – will continue for as long as we all live."

Whiley's childhood was therefore far from normal, although when the family moved to the Althorp Estate, home of Earl Spencer, brother of Princess Diana, to run the village shop and post office, life was easier. By then Whiley had begun swimming competitively, which she kept up until she was 15.

"I did sometimes yearn for my own space so I pushed myself to swim for Northampton. Dad would get up at 5am after yet another sleepless night with Frances to take me training, then he'd be off to work on a building site. An amazing, amazing man! Mum learned sign language so that she could communicate with Frances.

"I can't tell you how much love and respect I have for my parents and my grandparents for creating such a fantastic family.

"That's why I always knew I wanted a big family. I kept telling Steve I wanted four children. He'd have been happy with three but now of course he's besotted with Coco, who Mum looks after when I'm at work.

"Actually, you know, Noel Gallagher's responsible for Coco. I bumped into him and his girlfriend Sara, shopping in Selfridges. He was looking radiant. He and Sara had their new baby boy, Donovan, with them. Little Donovan was just weeks old, and Noel and Sara were so happy, and made it look so easy, cosy and fun, that I decided then and there that the day had come. In fact, when I announced I was pregnant I texted Noel and told him it was all his fault!"

Amid the happiness comes sadness, too. Whiley is a carrier of the Cri du Chat gene. She was tested for each of her pregnancies, and that's why she didn't want her Dad to discover she was pregnant again until she'd had the results of her tests back. "I would have terminated a pregnancy if the tests had proved positive, because I know everything the condition can involve," she says.

Stirring her coffee thoughtfully, she says: "Certainly, having Frances made life pretty difficult." Still. She can't talk about her sister without a big smile on her face. "She's brilliant now. Steve and the children adore her and she adores them.

"She was jealous when India came along, of course, and she'd hit her when she was a baby and I'd lose it and hit Frances back, although I've never once seen Mum or Dad lift their hands to her and often their lives were a total nightmare. But we got through it. Steve and I are so proud she's part of our lives."

Every chapter of My Life in Motion ends with a playlist, the music that has been the soundtrack of Whiley's life. I ask her for her heritage track. "Oh, The Platters' Smoke Gets in Your Eyes – Dad was crazy about this 1950s a cappella group and I must have heard this a million times when I was growing up."

The Whiley-Morton family anthem?

"Elton John's Tiny Dancer. Steve first played this to me. Now, someone will put it on in the kitchen and then, one by one, we'll all drift into the room until we're all there, belting it out."

Then she says quietly: "I'm so blessed. We've just had one of those golden weekends. It was raining so we played board games and had a lovely Sunday dinner together.

"I looked round at all of them, playing Monopoly on the floor, making each other laugh, Coco was on my lap, and I thought, my God, I'm so lucky. It's all come good."

So it's The Waltons rather than The Osbournes? Whiley laughs, then says: "More Little House on the Prairie."

• My World in Motion by Jo Whiley is published by Virgin Books, priced 18.99.

• Jo Whiley will present coverage from the Glastonbury Festival on BBC2 this weekend.