THE road to romance rarely runs smoothly, although one stretch of the M6 is reportedly all the better for the 2.5 million copies of mushed up Mills & Boon books incorporated into the mix of asphalt and Tarmac when it was built.

Pulp fiction of this sort - unsold novels reduced to a paste at a recycling factory - is a vital ingredient in road construction apparently, but don't be fooled into thinking this brand of red-hot romance is dead and buried, fit only for motorway concrete. Far from it.

The company, started by Messrs Gerald Mills and Charles Boon in 1908, marks its centenary this year and continues to flourish, churning out purple prose at the annual rate of 130 million books worldwide.

In the UK, one is sold every three seconds and the pass-on rate, via jumble sales, boot sales and charity stalls is just as high. With readership on such a high, the company's thirst for new authors is stronger than ever.

For many authors, their career took off sitting at the kitchen table, snatching writing time to wallow in testosterone overload and love conquering all while bringing up a family.

Mills and Boom Ltd started as a general fiction publisher with Jack London and PG Wodehouse among its authors. But the Depression and then World War Two brought a surge in demand for romantic fiction, which eventually eclipsed all else.

Despite criticism of formulaic writing, the 70 titles published each month fall into 12 distinct category series, ranging from the original soft focus Romance through to the thriller-style Intrigue and the downright raunchy Blaze.

True, the overall theme of smouldering passion remains immutable as alpha male heroes and feisty heroines jump through the compulsory hoops of attraction, conflict and resolution, but the reassuring familiarity is what keeps the readers coming back for more.

Mills & Boon is the book equivalent of comfort eating - and there are times when we could all do with a little of that. "I do like a bit of romance," admits Therasa, 44, who picked up her first Mills & Boon on holiday in the Greek islands several years ago.

"They are a lot racier than they used to be - some are so over the top sexually, they make your hair stand on end.

"One thing which really gets me is that the characters are too good to be true. But you don't want some fat bloke with spots, do you, so I cope with it," she says.

At Salisbury Library, 42-year-old Jill goes faintly pink as I catch her selecting one of the Blaze titles from the shelves. "It's the stuff you read because you don't have to think about it," she offers as an explanation. "It's definitely escapism - you can forget your everyday stresses."

Salisbury Library says the books themselves, especially the large print versions, remain popular with their borrowers.

On Salisbury market, Rod Smith, of Rod's Book Exchange, has two crateloads of second (or possibly third or fourth) hand copies that you can pick up at the bargain price of six for £5.

"Not half," he responds, when I enquire whether they are still popular, "and not just with the older people, it's all age groups. "They are all after the most recent books. Betty Neels used to be very popular - somebody brought in a whole collection of 170 Betty Neels and they'd all gone in just four days."

Neels was one of the company's most successful authors, selling more than 35 million books in the days when virginal heroines resisted the hero until the very last pages when the wedding was in the bag.

But today's writers have moved with the times.

Virgins are few and far between - the bedroom door swung open years ago to expose sexual gymnastics beyond.

Regardless, one element remains a constant - graphic description might have replaced coy sexual euphemism, but a happy ending is certainly guaranteed.