Channel 4 is to bring mass public masturbation to the small screen.

The broadcaster - once led by Michael Grade, dubbed "pornographer in chief" by the Daily Mail - has commissioned a documentary about the UK's first "masturbate-a-thon" as part of a series of programmes dubbed "Wank week", MediaGuardian.co.uk can reveal.

In what must surely be one of the summer's more bizarre events, hundreds of people are expected to gather in a hall in central London on August 5 to pleasure themselves in aid of charity.

The organiser of the event, the San Francisco-based Centre for Sex and Culture, has run mass masturbation events in the US for the past five years to raise money for safe sex groups and plans to replicate the formula in the UK.

Cameras from independent production company Zig Zag, which made Essex Boys for ITV1, will follow the organisers and participants for a 60-minute film, which has the working title of Wank-a-thon. It is expected to air on Channel 4 towards the end of the year.

The event will encourage Londoners - both male and female - to sign up sponsors and head to Clerkenwell in order to masturbate in front of hundreds of others.

Zig Zag said in its blurb for the show: "This year it's time to bring the event across the pond to see if the great British public can embrace mass public masturbation. It's time to find out if the only things allowed to be stiff in Britain are upper lips."

Prizes will be on offer for those who clock up the most orgasms and those who can masturbate the longest - the current record, according to the organisers, is a chafing eight-and-a-half hours.

To qualify for the record, the organisers say "at least 55 minutes of every hour shall be spent self-pleasuring by manual or sex toy stimulation" with participants getting just five minutes to "replenish and renew".

Two other programmes will also air as part of the week, which has been commissioned by the Channel 4 factual entertainment commissioning editor, Andrew MacKenzie.

"Following on from the success of 'Penis week', we feel this is exactly the type of provocative and mischievous programming that Channel 4 should be covering in the 11pm slot. Masturbation is something many people do but not many people talk about," Mr MacKenzie told MediaGuardian.co.uk.

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