As a young child she planned to be a prima ballerina and (of course) won a place at the Royal Ballet School, but her mother was worried she would develop turned-out feet, so introduced her to riding. She was also good at painting, acting, piano - you name it - and says when she left school it was a toss-up whether she would go to the Slade School of Fine Art, the Royal College of Music, or Oxford. (Are you throwing up yet? I almost am.) She chose Oxford to read English, which she loved so much she was tempted to do a PhD on 'Henry James and moral bankruptcy', but then her friend Sophie Hicks got a job as fashion editor of Harpers & Queen and asked her to come and help. 'It was electrifying. So then the visual thing happened.' With typical Amanda luck, Sophie Hicks soon moved to Vogue so Amanda took over her job as junior fashion editor, which meant working with all the new designers, such as Bodymap, and photographers, such as Mario Testino. 'We'd shoot these things that were like fairy tales, really. But I was a difficult, tricky, over-idealistic editor who would dig her heels in and refuse to do things because they were too much like advertising, so at the point where I think they were going to fire me, I met John [Galliano] who was the visual response to everything I could have imagined - he did shows which were stories and adventures - so I went with him.'
Galliano couldn't afford to pay her, but by this time she was married to Lord Harlech and 'provided I had my train fare back to Shropshire, I had a roof over my head'. Her husband was Francis Ormsby-Gore, son of the British ambassador to Washington (she fell for his 'gypsy brown eyes'), but his father died in a car crash during their engagement so she became Lady Harlech on marriage. They had two beautiful children, Jasset and Tallulah, and were idyllically happy for the first few years, living on the family estate in Shropshire and spending summers at the other ancestral seat, Glyn, in North Wales. But, like so many aristocrats, they were land rich, cash poor, so Amanda kept working to pay the school fees and luckily when Galliano moved to Givenchy he was able to pay her more - her son went to Eton, her daughter to Cheltenham Ladies' College. Jasset is 21 and doing graphic design at Central Saint Martins, aiming to work in advertising; Tallulah, 18, hopes to be an actor.
But working in Paris meant Amanda was away a lot and her husband went into decline - according to Catherine Wilson of the Telegraph, 'From being a rakish, Heathcliffian figure, he descended into the demi-monde of alcohol and drugs.' He was convicted of drink driving several times and of possessing heroin on Crewe railway station. (His sister had already died from a drugs overdose, and his brother by shooting himself in the mouth.) Then one weekend Tallulah, aged eight, asked Amanda why this other woman was sleeping in Daddy's bed - apparently it had been going on for two years. 'I didn't want to get divorced, but at the point where your children are part of it, you have to do something. I would really love it not to have happened because it haunts you, it will never go away, and it is probably the biggest failure, and I have to live with that.'
As a peer, her husband's property was all entailed to the Harlech estate, so there was no question of her keeping the marital home. She had to rent a tiny cottage down the road and squash in with the children. 'It was hard at times, because they didn't have a big house like their friends: it was a shoebox. It meant they kind of lost their childhood early, but now they're really proud of me, and they come home often.' After the divorce she was 'an outcast' from the aristocracy, but she didn't mind - she rarely uses her title in England, though it comes in useful in Paris. Her ex-husband has since sold all his English estates (their old home was knocked down) and lives at Glyn. He has never remarried. 'I think,' says Amanda, 'he agrees with me that neither of us is very good at relationships. But we love our children, and that's the main thing.'
The end of her marriage coincided with, and in fact caused, her move from Galliano to Lagerfeld, but she couldn't say that at the time and Paris was abuzz with rumours. The same weekend she found out her husband was having an affair, Galliano was negotiating a contract with LVMH to move from Givenchy to Dior. 'I understand,' she sighs, 'that anybody who has just got the job of his dreams is not going to say: There's this English girl that I need on the payroll. And I remember ringing up and saying, "Don't do this to me! I really need to be financially independent now!" And Karl Lagerfeld knew I was having problems and all he said was: "Look, get Dior to take you seriously. I'd love you to work for me, but you have a very special relationship with John, and I respect that. But this is what Chanel would offer you. Take this contract to Dior and say, 'Match this.'" So I did, and they rang back and said: Is this a joke? So I asked round lots of friends, like Anna Wintour, and they all said: "Make a professional decision for the first time in your life, Amanda", and I did. It was scary. But I had to do it, I had to, I had nothing, and I couldn't go on working for 30 grand.' Was Galliano upset? 'Very. He saw it as a betrayal.' But they have gradually become friends again, especially since the death of Galliano's assistant Steven Robinson last April: 'Steven was his right-hand man, and it was awful. Then Isabella [Blow] died - it's been a bad year.'
At first she found working for Lagerfeld very different to working for Galliano. She and Galliano had started from scratch together so they were almost like brother and sister, and part of her job was to boost his confidence and say, 'You can do it!' Whereas Lagerfeld was old enough to be her father and already knew he could do it: he had been Kaiser Karl presiding over his court in Paris for years. Moreover, the courtiers were not exactly welcoming. 'I'd come in to work and find they'd stuck up pictures of roast beef in my office, which they thought was funny, or I'd find them giggling over a portrait of me that Karl had done. But that's in the past. They've realised that I'm not a threat - I don't want their jobs.' Did she tell Lagerfeld about the pictures of roast beef? 'No, Karl is someone who believes you either swim or you sink. You do not expect him to protect you; you protect yourself.'
After her divorce, she had a long relationship with Neil Gittins, a local farmer she met hunting, but that ended last year. 'So I'm by myself. I am not good wife material because I'm fiercely independent and like to go off and do my own thing. I'd come back from a trip and be tired and have no more to give him. Or I'd be in the stables all day - we had eight horses - and crawl into the kitchen at seven, exhausted. Happily exhausted, in a way, because I'd managed not to think all day, kidding myself that manual labour frees the mind, but in the end it imprisoned mine. So, understandably, he found someone else. It's sad. Eight years is a long time.' How long did her marriage last? 'Twelve. Not doing very well, am I?'
No. In fact it rather confirms my theory that people who are very keen on clothes aren't very keen on sex. But then she perks up and says, 'But it's good for writing. You know that gap between where you are and where you'd like to be? Within that gap, there is an ache and an aspirational leap which is very good for writing.' Ah, her writing. She is keen to talk about it, and keeps raising the subject, whereas I have been putting it off for as long as possible. She has written the texts for two photography books, one called Palazzo by Lagerfeld, and one called Sicily by Michael Roberts, both to be published this autumn. They are good on atmosphere and metaphor - 'He felt isolated in this painted catacomb where meaning walked backwards like servants performing ancient rituals in the shadows' - but not so hot on plot or characterisation.
Palazzo started life as a shoot for Fendi perfume, but Lagerfeld got the picture he wanted almost immediately and still had the models for two more days, so Amanda suggested they use them to make a story. Lagerfeld told her to go away and write the script while he shot more photos, and amazingly, she says, his pictures fitted her script perfectly. Now she wants to do a follow-up, a ghost story, and plans to devote a whole week to writing it. 'Writing,' she says, 'is something I should have done more of, it's a form of coming home. It's something I've always done - I write a diary every day - but never committed to. But now, having someone like Karl saying: "Right, my publisher will publish your story, it will be illustrated with your watercolours, get going", that is what I'm incredibly fortunate to have, and that's what I will do.'
I get the impression she doesn't expect to remain a muse for ever, and is looking for a second string to her bow. Maybe she's wondering what she'll do if Lagerfeld retires, though she insists he will never retire and is never ill. She claims not to know how old he is - 'He's got to be younger than me in some respects because he has a helluva lot more energy!' - but if she looked him up on Wikipedia she would find he is 73. Does she ever worry about her future? 'Yes. And then I think: Well, I can turn the heating off and just write my way out of here, in my woollies. Joan Didion is a total icon to me, she's a brilliant writer and she just does it - she writes, and she's gone through hell. It's possible, isn't it?' It is. But for her to mention her own writing in the same breath as Joan Didion's makes me so furious I can barely speak. It was a terrible mistake to have worn the green necklace.