Clubs were an essential aspect of the 18th-century urban male lifestyle. Most of them found their common ground in ceremonial drinking and dining or were gambling venues, but a few allegedly focused on sex, blasphemy and deliberate ill-doing and became known as the Hellfire Clubs. In this book, Evelyn Lord examines the reality behind the legend.

However, once she has planed off the accretion of rumour, wild exaggeration and outright fiction associated with the 'Hellfire' name, there isn't enough information to fill a book. In 1720, the first Hellfire Club was founded by the Duke of Wharton. It went in for daring blasphemies such as playing cards on Sunday, reading Lucretius and eating pigeon ('Holy Ghost') pie. The Hellfire label was subsequently revived several times, but was more often just bandied about.

What Lord has in fact written about is a cross-section of the less respectable and more secretive 18th-century clubs. Drink, dressing up and politics feature far more heavily than sex and blasphemy. One thing 'everyone knows' about the Hellfire clubs is that Sir Francis Dashwood had one at Medmenham, called the Medmenham Friars. Interestingly, there turns out to be no evidence worth the name for any form of black magic or satanism at Medmenham or anywhere else.

Dashwood turns up so often that this almost looks like a book about him and his milieu. He also founded, or was a core member of, the Divan Club and the Dilettanti. He was an MP, as were many members of all three organisations, raising the question of whether their meetings were not more focused on sex and politics than sex and blasphemy, rather like Cliveden parties in the days of Profumo and Christine Keeler.

Blasphemy and black magic are part of the Hellfire legend but, Wharton's club aside, the evidence here is less of irreligiousness than of solidly Anglican bigotry. Several groups were demonised by accusations of pro-Muslim posturing: the 17th-century Tityre Tues allegedly had a leader called Ottoman, while the Mohocks' 'emperor' is said to have worn a Turkish crescent. Later, Dashwood's Divan similarly played with the transgressive implications of admiring the Muslim world.

However, the clubs' mockery of Catholicism was far more widespread, an expression of a general English belief that the Catholic world was riddled with corruption and hypocrisy, while monks generally, and friars in particular, thought of nothing but sex. In smart slang of the time, madams were referred to as abbesses, whores as nuns. When George Bubb Dodington called his luxurious house La Trappe, after the ferociously austere abbey of that name, it was not an anti-religious joke, but an anti-Catholic one. Lord is not good on all this.

Curiously, sex (plus drink and gambling) is more demonstrably part of the Scottish club scene, albeit in a peculiar, adolescent fashion: members of the Beggar's Benison in Anstruther met for drink, mutual masturbation and to admire a hired trollop's genitalia (touching not permitted). This suggests that 18th-century Scotland fostered an aspect of male sexuality more significant in some cultures than others: intense suspicion of overt homosexuality combined with a homosocial element to group activity and ritual.

Lord can be careless about details. She opens her chapter on Scotland with Robert Wodrow, historian of the Kirk, commenting that in Aberdeen 'a club of profligate men' mocked at a minister's preaching. By the next page, her narrative has shifted to southern Scotland, where it remains. But Aberdeen was an Episcopalian stronghold, so Aberdonian mockery of the Kirk was not necessarily part of the world of the Beggar's Benison, and Aberdeen and Anstruther are 90 miles apart.

Another problem is that other kinds of associations, gangs and groups of drinking cronies (the Mohocks or Rochester's friends) are lumped together with clubs. But an 18th-century club had a constitution, rules, officers, often uniforms and frequently premises. The fact that Rochester, Killigrew and Sedley got outrageously drunk at the Cock Tavern did not generate a Cock Tavern Club and whether Mohock was any more than a synonym for 'posh hooligan' is far from certain. The inescapable conclusion is that there is less to the Hellfire Clubs than meets the eye.