In a small, unprepossessing radio studio at Broadcasting House in London, Kirsty Young sits opposite Sir David Attenborough and questions him for more than an hour (which will be cut to 45 minutes), interspersed with eight of his favourite musical choices, for this week's 70th anniversary of Desert Island Discs, the world's longest-running factual radio programme.
Two national institutions are colliding. For Attenborough, it's his fourth time in the hot seat, a record he shares with the comedian Arthur Askey. "I did it for a mixture of vanity and compliment," he says.
"Listening to the signature tune in the studio, I realised again how beautifully orchestrated and played it is, evocative of languorous lying in the sunshine."
For Young, it's another edition of "probably the best job in the world". Six years ago she became only the fourth presenter, following the show's originator Roy Plomley, Michael Parkinson (1986-88) and Sue Lawley (1988-2006).
Attenborough was interviewed twice by Plomley (May 1957, March 1979), whom he remembers as "affable, a very jolly and civilised chap, who said, 'Let's be serious about your record choices,' so you selected music that illustrated a particular time in your life.
I don't have profound memories of Sue [December 1998], but Kirsty is more serious than Roy. She's a marvellously beguiling interviewer who asks penetrating and difficult questions. It's always flattering to be asked, 'Tell me about your innermost feelings.' I think, 'Good gracious, do people really want to know?' How frightfully flattering."
Young combines empathy with a seductive toughness in a deep but soft Scottish burr (she was nicknamed "Old Man River" at school, and sacked from the choir), which brings out the best in her castaways.
"Although the premise is phoney - sitting in a studio talking to each other - I don't think I'm deluding myself when I say you can establish connections," she says. "I'm constantly surprised, and delighted, by their frankness and honesty.
"It has a lot to do with the intimacy of radio I don't think it would work in any other medium - which I help enhance if I'm doing my job properly. Music is an emotional short cut to the soul, helping people become closer to who they are. It would be difficult to muck up because I'm working with such good material - men and women who really want to be there.
"I'm not going to skewer them but they anticipate a few uncomfortable questions because parts of all our lives are uncomfortable. I drew breath when I heard Sue Lawley ask Gordon Brown if he was gay and thought, 'Good for her.' There are no questions I wouldn't ask, although I'm not going to probe someone's cavity until there's blood all over the floor. I prod gently. I'm not a neutral observer. I might say, 'Oh, come on,' if I don't believe an answer, and that's an editorial judgement. Everything is subjective, even news."
Roy Plomley, who presented 1,784 editions over 43 years (and was a guest twice), took guests to lunch beforehand at his club. "I'm sure some got half-ratted on a couple of bottles of claret and a digestif," says Young.
"After him, there was no hospitality. Sue Lawley managed to convince them we should at least have tea and biscuits." I decline tea and we go to the Dean Street Townhouse in the West End, where she has a Bloody Mary.
It's part of her husband Nick Jones's Soho House chain, which he founded in 1995 and the day we meet it's announced he's sold half his remaining 20 per cent holding for £25 million. No wonder she's relaxed, charming, sassy and sardonic. She laughs a lot, is naturally inquisitive so can't stop twisting the conversation to ask questions.
She's adroit at allowing you into her own life, warts and all, with just enough confiding information to keep further intrusiveness at bay. At first she was accused of dumbing down the programme, of being an "auto cutie", "ruthless, disloyal and chillingly ambitious". Alternatively she was called "too nice".
"What was all that about? I was fortunate to start in Scottish TV where I got it in the neck just for being a woman on telly - people camped outside my door, or paid friends for stories, which upset me at the time. But it was a brilliant baptism. I learnt that if I become preoccupied with what people write, it's the road to hell. I'd only be pissed off if my producer says I'm not doing the programme well enough."
She brings a lightness that discourages guests from trying too hard to choose the "right" music. "They want to have a bit of fun rather than believe they' ll be judged or it's an epitaph. I've been surprised - particularly when David Dimbleby said he'd like to take me as his luxury."
Few have declined invitations. Mick Jagger is one. "This would be the right time to do him because there's more perspective when you're not in the white heat of success. Dawn French would be good, and Dustin Hoffman. Scientists are wonderful; they usually haven't been interviewed.
"Science is rock 'n' roll, so sexy. Politicians are awful, especially when they have the responsibility of office, because they have to be careful. More than anything you want guests to be honest, which is difficult because we all have a carapace, to protect our version of ourselves."
She was born in East Kilbride, near Glasgow. Her father, a policeman, left when she was a few weeks old and her sister, Laura, was three. "I met my 'genetic father' - antiseptic phrase - just once, when I was 16."
She is silent for a long while, and then apologetic. "I'm straying into other people's territory here, so I'll say no more. Is that OK? My father was the man my mother remarried [a carpenter, John Young].
"Here's a funny thing - not a fully formed thought - but I read profiles of women in the same profession as me, and at various points a parent left them. There's always something which fires people forward to ambition, restlessness. There's grit in the oyster for those who end up with the pearl.
Today, David Attenborough said his father was a demanding man who insisted he get a scholarship to Cambridge to study zoology. He said if you don't, it's probably not worth going. Isn't that brilliant?
"My early years had a profound effect on me that I didn't care to examine until now. I've never been to a psychiatrist but I'm sure we'd get there after a few sessions. I'm in a show-off profession and very confident. But if I'd seen my family disintegrate, I'd have had a sense of abandonment, a feeling I was not good enough.
"I've benefited incredibly from my mother, who is effervescent and stoic - an interesting combination. Life is complicated. It's mostly never as it seems. "There's a lot of talk about happiness at the moment [the Government is spending £2 million trying to quantify it]. I don't want my children to be 'happy'."
She has two daughters, Freya, ten, and Iona, four, and two stepchildren, aged 16 and 18. "They'll be bloody lucky if they glimpse it now and again. I want them to be content and have self-worth."
She became interested in broadcasting when, as a precocious 11-year-old, she saw Donald MacCormick present Newsnight.
"I was fascinated that a Scot did it. I wouldn't have had the balls to think I could. I was directionless, cursed with a very bright and beautiful older sister who was good at everything without trying. We might have ended up never speaking, but she's my best friend. All the teachers were disappointed I wasn't like her, so I thought, 'I'm going to be me.'
"Laura was accepted by every university she applied to. I didn't want to be second best, so went off in another direction and all credit to my parents, they let me."
At 17, working as an au pair in Switzerland, she became bulimic. "I feel funny saying it because I'm now a different person Although it was horrible, I don't want to overplay it - 'TV Kirsty's bulimic hell' - because people suffer for decades. I was lucky. I talked myself out of it in six months."
After working in Scottish TV, she became a news presenter for Channel 5, aged 27.
"Here's the thing: I know I didn't get the job because of my looks, which are average, but because they thought I could do the job. Then, at the 1996 Tory Party conference, Michael Heseltine refused an interview because he said he didn't want a little a smartarse in a short skirt to get the better of him.
"I realised then if you're talking to the establishment, you have to accept their attitude and if that means wearing a sharp suit and looking businesslike, it's fine, much less important than all the other things going on in my head.
"Having children honed my ambition. I thought if I was going to leave them every day I'd better do something honest and stimulating. I changed my working life when my husband, who is unbelievably good at what he does, decided to expand his business. You can't have two parents away all the time, so I do my research at home."
She also introduces Crimewatch ("the definition of public service broadcasting, regardless of who is presenting it") and sometimes Have I Got News for You, "which still seems fresh as a daisy". She needs to work, she says.
"I don't think I'd like being 'Mrs Jones' all the time. I need a bit of my own selfish head-space.
"The idea that you have to be young and beautiful to be on TV is boring, although when you see Arlene Phillips being hoicked off, there's probably still an argument. It's not a drum I want to beat. I don't wake up and think I must storm the barricades, although I don't want to be told in ten years [she's 43] that I'm not allowed on television.
"I'll always be allowed on radio - I don't see why I shouldn't be doing Desert Island Discs until I'm 85."