HMS Discovery: A Love Story contains scenes of flagellation, men undressing and frolicking in a river and a naked man apparently performing a sex act on another. While this may be hard for supporters of a party opposed to the "promotion" of homosexuality to swallow, Mr Barnbrook's transgressions get worse: the 58-minute film, made in 1989, is described as "Marxist" by one film website.
"It was an art film, end of story. It was not a bloody porn film," said Mr Barnbrook, now leader of the opposition on Barking council. "The only nudity in it is a couple of guys running in a river. It is not about homosexuality. It is about sexuality. Anything to do with my past politics or my past work, I am not interested in commenting on."
The existence of the film was first revealed in the Guardian before last year's general election, when Mr Barnbrook stood as a candidate in Barking. According to one cinema listing, Mr Barnbrook also starred in and co-wrote the film.
But yesterday he denied penning erotic poetry set to the footage, which includes the lines: "It bares you like a foreskin's folds" and "Open-mouthed, I shall dream of altar boys."
Mr Barnbrook was a painter, conceptual artist and art teacher before turning to rightwing politics. Searchlight, the anti-fascist organisation, has suggested he was also a Labour party member at one stage. Fellow extremists appear to take a dim view of Mr Barnbrook's colourful past. On one rightwing website, a poll has been created next to a picture of the BNP man asking: "Is this a poofter or what?"