Focus: A textbook case of hidden gold

HE IS Britain's best-selling living author and one of the most successful writers of all time. His books sit on the shelves of every dreaming suburban housewife, each one tempting the reader with its graphic detail and descriptions of an ideal world. More than 40 million copies have been sold over the past four decades, outstripping Wilbur Smith, Barbara Cartland, Dick Francis and even the late Catherine Cookson. If you've always harboured dreams of making a quick million by writing a blockbuster, the books of D G Hessayon are those you would do best to emulate.

You would be forgiven for asking, "D G Who?" Dr David Hessayon, PhD (Botany), is one of a select circle of men (they all seem to be men) who write quiet bestsellers, unlikely books that sell in enormous quantities over the years without ever hitting the Bookwatch charts. Mr Hessayon is the author of The House Plant Expert, that prosaic, rigorous guide to how to keep geraniums pert and African violets lush during their fleeting acquaintance with the TV or mantelpiece. That and the dozen other titles in the Expert series (The New Rose Expert, The Greenhouse Expert, The Fruit Expert, etc) have given him an influence over the nation's gardens far greater than anything Charlie Dimmock or Alan Titchmarsh could dream of.

They have also made the botanist from Essex, who used to be chief scientist at Pan Britannica Industries, (the firm that makes Baby Bio), an undisclosed but extremely respectful amount of money. "Even if he's getting just pounds 1 from every book he sells," says a publishing executive awed by the botanist's output, "he's sold 14.5 million books this decade alone, which would make him one of the richest authors in the world."

Mr Hessayon has been writing his illustrated books since 1959, when Be Your Own Gardening Expert made its way into the grateful gloved hands of Middle England priced 1/6d (7.5p). Romantic thrillers are clearly not the only route to blockbuster millionaire-hood.

There are other quiet bestsellers whose royalties far exceed the fantasy of the first-time novelist. A prime example is Physical Chemistry by Peter Atkins. Published by the Oxford University Press, the book has sold more than half a million copies since it came out in 1974. An OUP source says that, with the current sixth edition priced at pounds 26.95 for the paperback, Physical Chemistry has made Mr Atkins a millionaire. It is a standard text for undergraduates across North America, southern Africa and Australasia, as well as Britain. With the sales of its racily-titled successor, Inorganic Chemistry, now being prepared, the ouevres are likely to make the 58- year-old Mr Atkins, who is described by a friend as a "superman author who never stops", wealthier than any of his more prominent Oxford university colleagues.

Two other authors who have jointly made a fortune - estimated at more than pounds 1m - from an unlikely publishing venture are Tony Hope and Murray Longmore, who had the idea when they qualified as doctors in 1985 to pen a simple-to-use guide for all young doctors. The result, the Oxford Handbook of Clinical Medicine, has sold more than 600,000 copies, and is an essential part of any doctor's kit.

Norman Davies, professor of Polish history at the School of Slavonic and East European Studies in London, published the erudite Europe: A History in 1996. "It sold like hot cakes," says Amy White, marketing manager of the OUP. More than 100,000 copies have been snapped up worldwide in three years, at pounds 25 a copy. It is a useful earner for Mr Davies, even given academic royalties (usually less than 10 per cent, sometimes under 5 per cent). "Often it's a surprise when an academic book does well," adds Ms White. "But in this case we knew we were on to a winner". Any comments by the late philosopher and jurist H L A Hart about the sales success of his 1961 book, The Concept of Law, remain unrecorded, but it is one of the grandfathers of the quiet bestseller, notching up 92,000 copies in its first edition.

In a rare interview, Mr Hessayon says: "I've had a long-standing fascination with illustrated books and my prime motivation was to give simple-to-understand information to people who wouldn't dream of reading a standard work on gardening. It certainly wasn't about money and it certainly wasn't the wish to write a bestseller." Mr Hessayon lives in a mansion in a pretty, rural part of north Essex. He has 27 acres of gardens, which he tends with the help of a gardener. It was not gardening but the love of a particular genre of book that inspired him.

"I've been writing illustrated books as long as I can remember," he says, his sentences as crisp and trim as the simple advice in his books. "My first school expulsion occurred when I was four. I insisted on working on one of these books when the teacher wanted me to play with Plasticine."

He revels in his anonymity. "I have worked very hard to keep it that way. I turn down all invitations to appear on television shows and radio panels. This means I can have a life, and I am always reminded of this fact when I walk around the Chelsea Flower Show unmolested."

He continues to produce books. "I don't have to write for the money (which I have) or the prestige (which I don't want). It's just that I still have got something to say and I just don't seem to be able to get away from the need to design colour pages and fill them with words."