Fay Weldon is drinking a cup of instant hot chocolate and talking about marriage, divorce and reconciliation. Just last month, her husband claimed she had fled their home to get away from a noisy neighbour. Then the author of Life and Loves of a She-Devil, Puffball and The Cloning of Joanna May (on ITV later this month), and Growing Rich (a TV series next month) announced that she had actually filed for divorce from her husband of 30 years, Ron Weldon.

‘After many years of harmonious marriage . . . he to pursue his painting, me to pursue my writing,’ she said at the time.

Now, four weeks later and speaking extensively for the first time of the breakup of her marriage, she says: ‘I very much hope that we haven’t permanently split up. It seems to me unlikely that anything that drastic will, in fact, occur.’

She spent Christmas Eve dinner and Christmas Day in Ron’s company. ‘We are getting on, increasingly, rather well, so we will just have to see what happens next.’ She gives an end of subject look.

She relents, with gales of defensive giggles and genuine amusement, and says that she left the matrimonial home because it’s easier to move a pad and pencil than an easel and paintbrush. (Former antiques dealer Ron metamorphosed only five years ago into a painter and jazz trumpeter.) ‘He needs light and all I need is a patch of floor. Anyway, I have a nicer nature because I’m more flexible and, you could add, ‘impetuous’. ‘I have too much respect for him to say a word against him. Let’s just say differences in perception of politics, of what morality consists of and of aesthetic sensibility made it difficult for us to function under the same roof. We used to have incredible arguments on the stairs about the nature of creation.’

The 60-year-old author who is currently working on a BBC bible (series blueprint) looks tremendous. She has been dieting and doing Calanetics from videos in the sitting-room and taking hormone replacement therapy. ‘I can’t understand why everyone doesn’t have HRT.’

The feeling that whatever is natural is somehow good and you shouldn’t interfere, perhaps? ‘Nature’s only interest is in having you procreate, then it throws you away. But I do not wish to be thrown away. I don’t even want to die.’

But she puts on weight and takes it off repeatedly. ‘I never thought I was obsessed with my size,’ she says, indignantly. ‘It’s not something that rules one’s life.’

She returns to the subject of Ron. ‘I could say, I suppose’ – cavernous pause – ‘that I cannot live any more with three dogs, 16 hens and 18 sheep, and a hen in the dog food.’ She laughs, ironically.

But these are merely symptoms of an underlying problem. ‘Yes, the problem of what you spend your energies on. I have a gregarious nature and like talking to people and listening. I am a very sociable person. I like to expend my energies on the outside world and he likes to spend his on an interior world.

‘It becomes difficult for me to put up with him. It is also very difficult for me to put up with not being with him and very hard for him to put up with not being with me.’

They always had their fairly basic differences in attitude. ‘But we managed, somehow, to overcome them.’ The divergence, however, became exacerbated with Weldon’s growing celebrity. ‘The differences do get more acute as my public face becomes better known. It becomes more difficult to live in a world which is cut off, because the outside world intrudes. You also become answerable for your actions.’

She doesn’t think the relationship had become destructive for her. ‘But I think it may have become destructive for him. We have been married for a long time and it is extremely difficult to separate yourself from another person, to know to what extent his views are mine and mine are his. ‘If things go wrong, what should be working constructively begins to work destructively and it is important to have a high opinion of the other person, or a good opinion. And if that isn’t available for both partners, you begin to see yourself out of the other person’s eyes and you may not like what you see.

‘The other person may be completely right. But you would very much hope you could get them to turn around.’

The woman who once said she’d rather be in prison than trapped inside an unhappy marriage regards marriage as a very serious affair, not undertaken lightly, and unhinged with great difficulty.

Her peace negotiations with Ron are at that delicate stage when they could break down. ‘It might,’ says Weldon, scratching her head and looking to the side, ‘even be a little like the Arab-Israeli peace conference.’ She feels she is sitting there while the Israelis stalk up and down making wild gestures. Ron lives up the road (the occupied territories) in the ivy-clad house she moved out of.

She’s living in the neighbouring Somerset village of Pilton in a dear cottage (‘rented accommodation,’ as she says crossly) with a river at the end of the garden, his paintings on the walls, unmade beds and a sloppy mess in the kitchen. (She spends half her time in Somerset and the rest in a terrace house in Kentish Town. Curiously, she says she is going to move back to London at Easter.) So what is going to make it possible to go back and function under one Somerset roof? ‘One of us has got to bend.’ And will it be her? ‘Well, you sincerely hope . . . you don’t know . . . it depends.’

Throughout her talking about her marriage, one gets the feeling she doesn’t know whether she is coming or going. She takes a sip of instant chocolate, enjoying the chemicals. (You feel she’d rather that than Go to Work on an Egg, the slogan she created when she was a copywriter. ‘When I get to Paddington and take a deep breath of London air, I think it’s wonderful.’ Ron, by the way, liked lentils and home-baked bread.) Weldon is wearing a dusty pink jacket, with shoulder pads that hunch up around her face. She is on the short side, fleshy, with a huge bust, and blue, blue eyes that are upward tilting and set in an open face. Her face is pretty and expressive, but she is not photogenic. Her eyes can look sad, but her face has the expressions of someone who thinks life is a big joke. She spent her early years in New Zealand. Her father was a doctor and her parents divorced when she was five years old, thereafter living in different parts of the country. Weldon lived in an all-female household with her mother, older sister and grandmother.

‘Life was very hard and we had to survive. My mother had to support two children, which wasn’t easy.’ (Her mother, a romantic novelist, ended up running an advertising agency.) Aged 14, Weldon came to England and felt ‘in exile’.

When she was 17, her father died. She hadn’t seen him since she was 14. What was that like for her? ‘It was dreadful, dreadful. I mean shattering to the extent that you don’t quite recover from it properly.’ She is touched, caught unawares by the question, without defences or automatic answer. ‘When there’s been that gap, it’s very hard to come to terms with the loss of somebody you never really knew, because you only knew them when you were a child. It’s very difficult to come to terms with that.’ She sounds enormously sad. She has tears in her eyes.

‘It was a major loss. But my mother is still alive.’ She lives near by and they see one another frequently.

We discuss Weldon’s health. Her heart sometimes beats at twice the normal rate beneath her generally unflappable and serene exterior. ‘I just go into hyperdrive if anybody upsets me.’ (She has plasters on her wrist today because it happened the previous night. As usual, she had to drive herself to hospital where she was wired up, given a cardiogram and an injection to slow her heart.) It wasn’t a call from the Annex (as she dubs her real home) that caused it, but rather matters literary. ‘Someone upset me on the phone about Angel Clare and Alec d’Urberville.’ She screams with laughter.

Hers is a condition that affects people who talk a lot and have loads of adrenaline and are constantly getting more done in a day than can reasonably be asked. She claims to like this stress. ‘Oddly enough most people who get it feel absolutely terrified, but I don’t.’ (She is a great coper.) It happens about three times a year, but more if she is going through patches of tension. ‘Yes,’ she looks reluctant, ‘it has been happening quite a lot recently. Christmas Eve was the last time I was in hospital. Ha-ha.’ She’s a Leftish, humanist, feminist and omnivorous reader – cheerful, buoyant and immensely likeable. Not the dark and miserable woman full of rancour and savagery that one might expect from her books. She also has extended senses – they might be called psychic by someone with a less scientific mind.

She has been a breeding machine (she laughs at the words) and has begat a Nicholas, Daniel, Tom and Sam. The first from a short-lived marriage to Ron ‘Number One’ Bateman (whose name she normally claims to have forgotten). ‘I just like children. I think it’s extraordinary to see what comes out.’ The youngest lives with her and she drives him daily to school at Millfield. To her surprise, she works with the others sometimes.

‘I do say to people that if you are going to be a writer, you’ve got to be a bad mother. But I think I’m a bad housewife and a kind mother.’ She used to feel great anxiety as a mother, and would weep from self pity and rage, feeling trapped by other people’s needs. ‘As you earn more, you’re not nearly so angry because you can always call a taxi and go to Harrods.’ On Weldon’s birth certificate, she is recorded as ‘Franklin Birkinshaw, boy’, and ‘boy’ is crossed out and ‘girl’ added. ‘Naturally, anyone would have thought I was a boy. Then my parents just called me Fay, having realised they were in error calling me Franklin.’

She smiles mischievously and suggests we go up to the Annex and pretend we want to buy a painting.