A British thriller about sexual deviancy and death is making waves at the box office. Alison Jones caught up with director Oliver Blackburn to discover who’d want to punch a donkey.

The late night television schedules and small sister channels to the terrestrial big five are awash with tales of teens behaving badly aborad.

The combination of exposure to sun and mind-altering substances and the shedding of inhibitions results in car crash TV that would horrify the parents of the participants if they caught wind of the fact their little angels were involved.

New Brit flick Donkey Punch takes the Ibiza or Ayia Napa unleashed premise and amps it to 11 with a graphic and very bloody depiction of what can happen when good sex goes bad.

The title is taken from a position – which if not completely mythological is certainly inadvisable. It is alleged, among the smutty minded, that a blow to the back of the neck delivered to the person in front during doggy-style sex enhances the experience for the person behind by causing a reflexive muscle contraction.

The claim has been rubbished by medical experts, who also point out that the end result is more likely to be paralysis or death than heightened pleasure.

But it is still the type of tall tale that gets told at stag parties, which is where David Bloom, the co-writer of Donkey Punch, first heard about it and told his fellow script writer, and the film’s director, Oliver Blackburn about it.

“I remember him telling me ‘have you ever heard of this thing?’ and he told me what it was and we were both went ‘uuurgh’ but it just stuck in our minds.”

What gives the film its edge is that the action all takes place on a luxury yacht which is being crewed by a group of ex-public school boys, instantly creating an isolated setting that the participants are battling to get out of alive.

“David and I had been on holiday and noticed all these boats locked up and shut up and he noticed there were very young guys taking care of these multi-million pound pieces of kit,” Olly explians. “There was a story there and that was what we wrote.”

The movie features fours guys acting as crew on one of the breathtakingly expensive boats while it is moored in Mallorca. They meet up with three Northern girls on a weekend break and take them back for a quick cruise into open water.

Drinking, drug-taking and sexual frolics ensue. But when, in the middle of a mini-orgy, one of the boys delivers a fatal blow to one of the girl’s necks, the young hosts are anxious to cover things up by throwing her overboard while the remaining two girls are desperate to get back to shore.

Gradually things start to spiral out of control and the body count starts rising as the various parties start fighting dirty to get what they want.

“We love the films of Roman Polanski and Neil LaBute and the way a certain type of male dynamic works,” says Olly. “We were reading reports of things like four footballers watching another footballer screwing a prostitute and telling them how to do it, and it was like a Neil LaBute play. There’s no sub-text there, that is just male sexuality. A lot of that fed into our minds.”

This might be crediting the film with more psychological depth than it actually possesses. What it is is an entertainingly nasty little addition to what one might call the boat thriller genre that is far more realistic than the average slasher movie.

“The big difference for me between this and Dead Calm or a lot of other genre films was we made a decision that there was going to be no monster, there was going to be no psychopath, nothing that was going to come in and bump these kids off, which is what it would have been if I had made this in America.” says Olly.

“It was going to be a film about some really normal people who get involved in a terrible situation and then kind of fragment trying to deal with it.

“We set this film in a very specific community of people who crew boats so we went to Palma, which is where the film is set, and we looked at the Marina and spoke to people there. We met with a clinical psychologist and discussed trauma and shock situations and what characters would do and the drugs they would take. I went up to Leeds (where the girls come from) and spent time in the clubs, just seeing what women looked like and what they wore.”

Despite the Balearic location, filming actually took place in South Africa.

“The film was shot in February but is set in summer. We just needed somewhere there was water and decent climate, that is how we ended up in Cape Town.

“It actually worked out really well. They have fantastic crews down there and the exchange rate is so good that I am not sure if we could have achieved what we achieved in terms of the look of the film, the stunts and the effects and everything shooting in the Northern Hemisphere.”

He points out that the yacht they were loaned to film on was actually worth four times as much as their £1 million budget.

“It is the biggest boat in South Africa,” says Olly. “The bond company were terrified because if we sank the boat, which I have got to say on a couple of occasions was a possibility, they would be absolutely shafted.

“I think the owners were just told it was a thriller on a yacht, I am not sure if we went into details.”

Had they been aware of the carnage that was to take place on board they might have been reluctant to let the cast and crew borrow their pricey toy and cover it in more gore than Sweeney Todd’s basement.

Oliver admits that, by confining the action to one location, they had to get creative in terms of what potential weaponry the reluctant combatants had access to.

“The (idea for) the final death came fairly late on and that was inspired by being on board thinking ‘how can I kill someone?’

“The flare was planned from the start but once we researched what a flare actually does in water, that released a great burst of energy in me and my stunt crew about how deeply unpleasant we could make it.

“There is a gun in the film that never gets used and that was a conscious decision. I think a harpoon gun came up but we just thought ‘we can’t go there’.”

They stuck with the name of the film, even though they knew only a few people would understand the reference.

“I wanted to change it,” Olly admits. “I am very glad that I was stopped from doing that. I just think it is so enigmatic. It’s two words which don’t belong together.

“In America everyone knows what it is, which tells you a bit about America...

“I think that every time anyone sees a title and wants to know what it is, maybe goes onto the internet to look, that can only be good for your film .”

* Donkey Punch is in cinemas now.