Paper that sells smut with a smirk: The 'News of the World' is celebrating its 150th anniversary. Michael Leapman reports

STAFFORD SOMERFIELD, editor of the News of the World in the Sixties, called it 'as British as roast beef and Yorkshire pudding'. To show that nothing much changes, Pat Chapman, under whose editorship the paper celebrates its 150th anniversary tomorrow dubs it 'as British as Sunday lunch'.

If being British means taking an obsessive interest in the shameful secrets of your fellow citizens, especially their sins of the flesh, then the Sunday newspaper has never been in any doubt as to its national identity. The special offer of 'naughty Victorian style undies' included in tomorrow's edition, each cheekily photographed, sums up its philosophy of smut with a smirk.

Over the years the newspaper has changed, as society and its morals have changed. But it has never lost the conviction that what people want to read about as they laze in bed on the sabbath is the seamier side of life, in particular the torrid lusts that hide beneath cloaks of apparent respectability.

And who is to say they are wrong? In the 1950s, with its slogan 'All human life is there', the newspaper reached an astounding circulation of more than 8 million, which meant that it was read in nearly half of all British homes. Today it sells 4.7 million copies a week, more than the combined sale of its two closest rivals, the Sunday Mirror and the People.

All human life may not be there, but for years the News of the World reported what the vicar did with choirboys in the vestry; unspeakable acts in the potting shed; the stream of 'gentleman callers' to a house in leafy suburbia.

Before intrusive reporting became the norm, the News of the World relied mainly on the courts for its articles. Its first issue, on 1 October 1843, reported a rape, an abduction, an attempted suicide, plus several assaults and robberies.

The divorce courts were a rich seam. In 1870, the paper reported the case of a military wife who committed adultery with three men, dressing in her husband's uniform for their delight. In 1963, the Duchess of Argyll's divorce, and the notorious 'headless man', provided an equal sensation. And in 1970, came the classic headline: 'Nudist welfare man's model wife fell for the Chinese hypnotist from the Co-op bacon factory'.

By then it was sending reporters on perilous missions to research their own articles. stories. 'I made an excuse and left' became its catchphrase, as intrepid men dug into dens of vice, always withdrawing moments before they were themselves dragged into the cesspools of shame. 'We buy a man, price pounds 5,' was a 1962 headline, while in 1988 the technique was used to embarrass Pamella Bordes, a Commons researcher and friend of Andrew Neil, editor of its sister sheet the Sunday Times.

By the Eighties it was necessary to link scandal with famous names for maximum effect. In 1986, a reporter trailed a prostitute to Victoria station, where she was given pounds 2,000 by a man acting for Jeffrey Archer. The 'confessions' of young women about their liaisons - inaugurated by Christine Keeler's 1963 account of her role in the Profumo affair - have embarrassed the likes of Sir Ralph Halpern and Frank Bough.

One of the paper's most significant years was 1969, when it became the first British title to be bought by Rupert Murdoch, laying the foundation for his present empire. He kept it in its original broadsheet format for a surprisingly long time, changing it into a tabloid only in 1984.

Mr Murdoch would have endorsed the message to readers in that very first issue 150 years ago: 'It is only by a very extensive circulation that the proprietors can be compensated for an outlay of a large capital in this novel and original undertaking; but they are confident that . . . the intrinsic merits, as well as the extraordinary cheapness (it cost 3d) of the News of the World will be duly appreciated . . . One of the great features of the publication is its extraordinary cheapness; and this great feature shall never be interfered with, on any account whatsoever.'