Jones was well into his middle age when his first big break came. Someone from Woman's Hour wanted an expert to come on the radio and talk about snails. Jones was the man. Then, in 1991, while still only a Reader at University College London, Jones gave the BBC's Reith Lectures, broadcast on Radio 4. Two highly popular science books and a television series or two later, and Jones had risen to become the best-known genetics expert in Britain.
Next Wednesday evening he hosts another television programme, a Leviathan documentary on BBC2 which looks back at a 1930s experiment on American maize that went drastically wrong. He warns, almost as an aside, that there are parallels with what is being planned now with genetically modified crops.
"People get worried about GM food but it seems to me for the wrong reasons," he says in the programme, looking out on an experimental field trial. "I have a worry and it's a biologist's worry. What we've done in this field is put genes in places they've never been before. There's a real chance they are going to get out. And what's going to happen to those genes in 20 years' time? The answer is, we don't know; there is a risk."
It is a tribute to Jones's celebrity status that his comments got the full tabloid treatment last week when news of the documentary emerged. "My fear on GM foods by genetics expert Jones", ran the Daily Mail headline. Jones's reaction to the fuss was, however, typically acerbic: "What are the buggers saying now?" (not being a natural reader of the Daily Mail). "God, it was only a small part of the programme."
Yet, whether he likes it or not, Jones has become a media darling. He has become something rarer than gold - a quotable scientist. His one-liners are infamous, and he uses the skill to good effect as he deftly sprinkles humour through his books and newspaper articles. He once argued that the bicycle was the greatest invention to combat genetic disorders, on the grounds that it resulted in more genetic mixing as a result of marriages between people living in different towns. (To illustrate the point, one of his favourite tricks when lecturing to students is to ask them to estimate how far apart their parents were born, and to compare that with the birthplaces of their grandparents.)
Jones is a natural journalist as well as scientist, which is well illustrated by his "intros", the crucial first sentence of an article. "Looking over my muesli into Camden Town, I am impressed (and enraged) by the genetical exhibition that urinates on the garden. I refer to the cats," goes one piece. "It is not a good idea to fight the laws of physics. Until I learnt that simple truth I used to climb mountains. Now I accept the Earth's attraction and do the natural thing by walking only downhill," says another.
He shares a mortgage (his phrase not mine) with an award-winning television producer, Norma Percy, and walks each day from his house in Camden, north London, to a run-down backstreet in Euston, where he is now ensconced as Professor of Genetics and head of UCL's Galton Laboratory. He is rather proud to show visitors the artefacts left behind by Francis Galton, the great, if eccentric, 19th-century scientist and founder of modern statistics.
Galton was a fanatical observer of inherited characteristics. His views on inheritance now appear dangerously obnoxious, given the 20th-century history of racial hygiene in Nazi Germany, and indeed the Balkans today. Galton attempted to construct a beauty map of Britain by furtively scoring the attractiveness of women in the streets of towns he visited. His 1869 book, Hereditary Genius, proposed a system of arranged marriages between men of distinction and women of wealth and beauty in order to produce a gifted race. It was the birth of eugenics.
More than a century later, and with just a few more years to go before geneticists finish the ultimate book of man by unravelling the complete DNA sequence of the human genome, genetics has become the hottest scientific subject of the age. The great writers on genetics and evolution, such as Stephen Jay Gould and Richard Dawkins, have taken full advantage of the public's fascination with genes. Their grand and eloquent essays and books, however, lack the cheeky quips and quirky asides that are a Jones speciality. His style is all about making things fun and amusing, a bit like how he is in real life.
He was born 55 years ago in north Wales and went to school on Liverpool's left bank (his phrase not mine), otherwise known as The Wirral. "I had two accents as a child, which accounts for why I don't have one now." His grandparents were strict Presbyterians and as a boy Jones spent interminable hours each Sunday listening to Welsh-speaking services. His mother was a bacteriologist ("she sensibly gave it up to have me") and his father was a physical chemist for Unilever who helped to invent Jif, the wonder cleaning agent. "My Dad changed more lives with Jif than anything I will ever do."
The young Jones buried himself in books - he had read all of Dickens by 14 - and took up birdwatching. His passionate interest in living things inevitably led him, like many other naturalists, to study biology. Next stop was the University of Edinburgh (eight years and a PhD), then a spell in America before returning to the sleepy backwoods of British academia. Oh, and then there were the snails.
There is nothing that Jones likes better - at least nothing he is prepared to admit to - than being half-way up a mountain, crouching down on all fours with his nose to the ground. Immediately after he won the Rhone- Poulenc science book prize of pounds 10,000 for his first popular tome, The Language of the Genes, Jones confided that he would spend the money on a snail expedition to his beloved Pyrenees. "Can't get a research grant to do it," he complained.
He admits to a curious fascination, if not love affair, with snails, particularly the ones with coloured bands on their shells, which can help evolutionists study the forces of natural selection. It is not unusual for biologists to specialise in a particular animal group, and Jones evidently enjoys the humour attached to his particular object of interest. His Camden home is littered with molluscan ornaments and one of his records on Desert Island Discs was the theme tune from The Magic Roundabout, which, older readers may remember, had a snail character called Brian.
The snicker-value of snails has not been lost on the media. One female interviewer for a Sunday paper couldn't resist making a comparison between the short, spry Welshman and his one-footed quarry. "He's unassuming but seductive, seditious maybe. Quite a sexy snail, but definitely a snail," she wrote.
Snail or not, the last 10 years has seen Jones rise to the dizzy heights of popular success. Two best-selling books, television appearances and even a minor role playing himself in a TV advertisement for a French car company, has given him financial security most scientists (and journalists) would kill for. But other than a house in the south of France, he displays no obvious signs of conspicuous consumption - or the arrogance of being a scientific celebrity. He still favours the tweed jackets and open-necked shirts of the staff common room and has a rich supply of self-deprecating jokes.
"My holiday is to stay in Camden Town," he once wrote. "I have a house in France, between Montpellier and Toulouse, where I go a lot outside term-time. It sounds pious, but it isn't really a holiday place because I go there to write and not to be distracted. I've got a fruit-fly project there and, as it's near the Pyrenees, there are snails as well."
He once went on a busman's holiday looking for the hairy-nosed wombat in the deserts of central Australia. "I really enjoyed it, absolutely marvellous. We didn't see a single hairy-nosed wombat, except in a cage outside a pub." The thing about snails is, they don't run away.