Scare tactics: The Hammer horror film posters with real bite

"Tit and fang" is how the poet Philip Larkin summed up Hammer Films' output and, give or take the odd ill-fated deviation from the formula, he wasn't wrong. Cobwebs, coffins, crucifixes, bats, bubbling test tubes, buckets of blood, crumbling castles, barely restrained cleavages: these were the emblems of Hammer horror and, against the odds, they scared the bejesus out of movie-goers in the late Fifties and Sixties.

The accompanying posters – now the subject of a new exhibition at London's Idea Generation Gallery – were the ultimate distillation of the genre. The aesthetic was pure B-movie, flipping two fingers at all notions of subtlety and elegance. Hammer posters were wilfully chaotic, crowded with cartoon-like figures and with typefaces designed to replicate dribbling blood or unspecified brown ooze. The taglines were appalling and brilliant: "Beware the beat of the cloth-wrapped feet!" shrieked the poster for The Mummy's Shroud, while Taste the Blood of Dracula exhorted viewers to "Drink a Pint of Blood a Day!".

Like the films they depicted, the posters' cartoonish style often masked some seriously explicit imagery. An early poster for Blood From the Mummy's Tomb featured an Egyptian woman with a severed arm standing pitilessly over a naked girl, dripping blood over her breasts and into her nether regions, as a serpent looks on. Others were just plain dirty. The poster for Vampire Circus was awash with thinly disguised phalluses. Looking at it, you get a sense of illustrators as cackling schoolboys pushing at the boundaries of decency to see just what they could get away with.

One of the most extraordinary things about the posters, says the author and Hammer aficionado Marcus Hearn, is that the majority were commissioned before the films were made. "Where most film studios used posters as a marketing tool to lure audiences, Hammer used them to reel in the studios," he says. "They were the bait that got Hammer the money to make the film."

Hammer's managing director, James Carreras, was a Wardour Street legend and a master salesman. His modus operandi consisted of thinking up a suitably sensational film title and then immediately commissioning the artwork to sell it.

"The illustrators had very little to go on," says Hearn. "There would be no script or storyboard. They'd get a call saying, 'We're doing another Dracula', and they'd have to use their imagination. An early poster for Dr Jekyll and Sister Hyde has got girls in tight jeans and T-shirts being murdered in the streets. It was only later that someone pointed out to Carreras that the story is actually set in the late 19th century."

Among the most prolific Hammer artists was the late Tom Chantrell whose posters were frequently more thrilling than the films they advertised. In the absence of a cast, Chantrell, who went on to design the posters for Star Wars, would get his friends and family to pose. In the poster for Dracula Has Risen From the Grave, he painted himself into the title role.

Nowadays, Hammer films are regarded by many as camp artefacts ratheer than celluloid treasures, and looked upon with slightly bemused affection. But in the late Fifties, Hammer heralded a golden age in the British horror movie, a time when cinematic terror was about gothic escapism rather than Blair Witch-style realism. The most commercially successful of all British film companies, Hammer was as defining a British film brand as James Bond and the Ealing comedies, revisiting many classic stories that Universal studios had made years earlier, but this time in glorious Technicolor.

The company made more than 200 films, including The Quatermass Xperiment, The Curse of Frankenstein, Dracula, The Hound of the Baskervilles, The Mummy and The Devil Rides Out. It made international stars of its leading men, Peter Cushing and Christopher Lee. Raquel Welch created an iconic image by squeezing into a fur bikini for the sci-fi extravaganza One Million Years BC, while Joanna Lumley came to a sticky end in the Satanic Rites of Dracula. In 1968, Hammer won the Queen's Award to Industry, an honour not bestowed on any other film company before or since.

There were those, however, who thought the films deeply unsavoury. Hammer thrived on the savage appraisals of reviewers who used words like "degrading" and "nauseating" to describe the generous helpings of lewdness and gore. The critic CA Lejeune wrote that she was "inclined to apologise to all decent Americans for sending them such sickening bad taste".

Hearn remarks that Hammer had much in common with Carry On films, another very British invention that was despised by critics yet stole the show at the box office. "Innuendo was at the heart of Carry On and suggestion and suspense was at the heart of Hammer," he says. "Although Hammer fought against the censors, they did them some favours when it came to longevity. When restraint was used, there was greater concentration of mood and atmosphere. But once the films became gorier and more sexually explicit, the whole thing started to unravel."

In the Seventies, money from the American studios dried up and the demand for Hammer films dwindled. As more sophisticated psychological thrillers such as The Exorcist and The Omen came into being, Hammer struggled to adapt. Throughout the Eighties and Nineties their films were rarely glimpsed, largely used as filler in the graveyard hours by television schedulers.

Lately, the company has been reanimated by the Dutch media magnate John De Mol, the wallet behind the Big Brother television franchise. After the quietly successful web-based feature Beyond the Rave, Hammer now has a series of films in production, including The Resident with Hilary Swank. But while they may reignite interest in the studio's back catalogue, these modern-day horrors are unlikely to have much in common with the Hammer of old. So perhaps now's the time to clench your stomachs and feast your eyes on Hammer's degenerate past, as the chances are you won't see its like again.

The Hammer Festival, which includes an exhibition of original Hammer horror posters, is at Idea Generation Gallery, 11 Chance Street, London E2, until 15 November. 'Hammer Glamour' by Marcus Hearn is published by Titan, priced £24.99