Mrs Buttle's son, Joseph, was born in November after she had been treated at the clinic, apparently with sperm provided by her lover. She gave a false name and told staff that she was 49.
Speaking exclusively to the Independent on Sunday, Professor Craft rejected calls for mandatory identity and age checks. "I don't want to see fertility clinics become like police states," he said.
Mrs Buttle was treated without a GP's referral, which the clinic asks - but does not insist - that patients provide. "There are many good reasons why women may not want their GP to know," Professor Craft said. "GPs' surgeries are not always good at preserving confidentiality. And some women will fear that their doctor does not approve of their seeking fertility treatment. We shouldn't put extra hurdles in their way."
Mrs Buttle first announced that she had conceived her baby without fertility treatment. Later, the truth emerged. It is likely, because of her age, that an egg donor was involved. Further confusion was then provided by her turbulent relationship with her lover, Peter Rawstron, who is thought to be the father.
Professor Craft said that a total of nine doctors, nursing staff and the required two independent counsellors took part in Mrs Buttle's treatment. None of them suspected her true age.
The Buttle case has divided medical and public opinion. It goes to the heart of the debate of whether fertility treatment, when privately funded, should be available to women whatever their age and personal circumstances. The NHS effectively rules out treatment to women over 37 on the grounds that the success rate falls after that.
The guidelines of the Human Fertility and Embryology Authority, which regulates fertility treatment, include the phrase, "the welfare of the child is the paramount consideration", although it is hard to see this as meaningful given that fertility clinics provide only basic checks on patients' circumstances.
The Professor, however, takes a robust libertarian view. "In the case of Mrs Buttle, a lot of the criticism came from people who judged that a single woman of her age living in the countryside was unfit to bring up a child. But she sounds jolly resourceful to me and anyway, it is not my place to moralise to her."
A workaholic of pleasantly eccentric manner, the man known to his staff as simply "Prof" says, "All women are different, just as all songbirds and symphonies are different. We don't try to impose regulations on them, do we?"
His is the only clinic in Britain to openly treat women up to 55 - the maximum age allowed by the HFEA. The Professor says he has no intention of imposing stricter rules. Anyway, he says, they would be ineffectual without the introduction of universal identity cards. "I could ask for a birth certificate. But patients might bring their sister's or daughter's. Similarly, we ask to meet the partner, but if a woman brings along her brother, how would I know?"
Would he have treated Mrs Buttle if he had been aware of her true age? "No, that would break the guidelines. But I would have no qualms about advising older women to go abroad. If a 70-year-old woman wanted a child, I would have some reservations because her nurturing time is likely to be short. But it's odd that no one ever asks about the age of the father, isn't it?"
Professor Craft has received support from a fellow specialist and frequent rival, the Labour peer Professor Lord Winston. The two men have been locked in a competitive battle for years, with Professor Craft responsible for the first test-tube twins and triplets while Professor Winston last year helped an HIV positive woman to have a baby. "Ian Craft has my sympathy in this case," said Lord Winston. "It seems to me that society has a prurient obsession with older women having babies. The vast majority will make wonderful mothers."
But Susan Bates, a protege of Professor Craft's, who is about to set up her own clinic in Cornwall, has some reservations. "Personally, I have difficulty with the idea of treating, say, a single woman in her 40s, using a donated egg. I will have a lower limit on the maximum age in my clinic."
Meanwhile, Tory MP Ann Widdecombe has called for tighter restrictions. "There is an attitude growing where all women have to say is 'I want a child' and they can have one," she says. "That," Professor Craft rejoins, "sounds perfectly reasonable to me."Reuse content