Britain's most high-profile gay police officer is to retire from the Metropolitan Police next month after serving more than thirty years.

Brian Paddick is to leave his post as a deputy assistant commissioner at Scotland Yard to pursue a career as a public speaker and author.

Mr Paddick, from south London, is also in talks about producing a documentary on policing.

His departure from the Metropolitan Police comes after he clashed with Sir Ian Blair, the Metropolitan Police Commissioner, over the police shooting of an innocent man mistaken for a terror suspect at Stockwell Underground station in July 2005.

Mr Paddick told the Independent Police Complaints Commission investigation into the Commissioner's conduct that officials in Sir Ian's own private officer feared the wrong man had been killed just hours after the shooting.

Sir Ian insists that he and his closest aides had no idea until the morning of the following day that the man, Jean Charles de Menezes, shot eight times by officers, was in fact an innocent Brazilian.

Mr Paddick, the highest ranking publicly gay police officer, is known to have thought he had been sidelined by Sir Ian last year and had become increasingly disenchanted with his position. He will leave on May 31.

He came to public prominence as the borough commander in Lambeth, south London, where he oversaw a pioneering scheme under which people caught with small amounts of cannabis faced only a warning about their conduct.

The then commander of the borough of Lambeth also got into trouble after it was discovered that he had posted controversial comments on the radical internet chatroom Urban75.com, under the tag name of "Brian: The Commander".

Revelations in the Mail on Sunday by one of Mr Paddick's former boyfriends led to him being moved from his job in Lambeth to a desk job.

James Renolleau, 36, claimed his partner of five years had smoked cannabis on more than 100 occasions at the couple's Westminster flat.

The allegation led to a criminal investigation but he was cleared of criminal wrongdoing in October 2002. Later a disciplinary inquiry by the Metropolitan Police Authority ruled there was no evidence to substantiate the cannabis allegations, but Paddick was never reinstated to his post in Lambeth.

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