film had been a major success for Hammer and, eager for a sequel, they purchased the rights to Nigel Kneale's follow-up before the BBC had even begun transmission of the new serial. For this adaptation, Nigel Kneale himself was allowed to write the first draft of the screenplay, although subsequent drafts were worked on by director Val Guest. The plot is a condensed but largely faithful retelling of the original television serial. The main difference between the two versions is at the climax: in the television version Quatermass blasts off in a rocket to confront the aliens in outer space, whereas in the film the rocket is fired, unmanned, to destroy the aliens' asteroid base. Returning director Val Guest once again employed many cinema vérité techniques to present the fantastic elements of the plot with the greatest degree of realism. Nigel Kneale was critical of the final film, mainly on account of the return of Brian Donlevy in the lead role. Kneale was unhappy with Donlevy's interpretation of the character and also claimed the actor's performance was marred by his alcoholism, a claim denied by Val Guest. Although Quatermass 2 was financially successful, its box office performance was eclipsed by the massive success of another Hammer film, The Curse of Frankenstein, which was to be the first of their many Gothic horror films. As a result, it would be ten years before Hammer adapted the next Quatermass serial for the cinema with Quatermass and the Pit (1967). Quatermass 2 was, however, the first film for which Hammer pre-sold the distribution rights in the United States, a financial model that would quickly become the norm for subsequent Hammer productions. Origins Writing Nigel Kneale had been unhappy with Hammer's adaptation of The Quatermass Experiment, partly because he received no extra remuneration from the sale of the film rights and partly because of the changes made in the film to his original television script. In the wake of his dissatisfaction, Kneale exerted pressure on the BBC to allow him to be more involved in the sale of the rights to his work. Despite being in the final months of his BBC contract, Kneale was allowed to collaborate with Hammer on the adaptation of Quatermass II. The first draft of the screenplay was written by Kneale with input from producer Anthony Hinds. Subsequent drafts were worked on by director Val Guest, as he had