Police decide not to prosecute the comedy gatecrasher who left royal security red-faced

The self-styled "comedy terrorist" who gatecrashed Prince William's 21st birthday party dressed as Osama bin Laden will not be prosecuted, Scotland Yard said last night.

Aaron Barschak's publicity stunt embarrassed police and prompted an urgent Home Office inquiry into the security arrangements around the Royal Family.

The 37-year-old comedian evaded officers from the royalty and diplomatic protection group guarding the event at Windsor Castle before jumping on stage and kissing the prince on both cheeks. He was only arrested when he demanded champagne from a waiter.

Mr Barschak, who was wearing a false beard, a turban and a pink dress, was initially arrested on suspicion of burglary, which covers unauthorised entry. He was later released on police bail after the incident at the African-themed party attended by the Queen and most of the Royal Family on 21 June. But Scotland Yard said yesterday that no further action would be taken against him following advice from the Crown Prosecution Service.

Nine police officers were served with notices telling them they faced disciplinary investigation. Chief Inspector Mark Goddard, who commanded the castle's security was moved to other duties while the investigation was carried out.

After the incident, David Blunkett, the Home Secretary, warned anti-terror chiefs that heads were "on the block", but insisted he was not looking for scapegoats. In a Commons statement, he said the security breach had exposed an "appalling failure" of policing.

Mr Barschak cut across the grounds of St George's School, which borders Windsor Castle, climbed a bank, shinned up a tree next to a 12ft perimeter wall and dropped 8ft into the grounds before scaling a 6ft garden gate leading to the palace's northern terrace.

He was stopped and questioned by police but talked his way in, claiming he was a guest who had got lost. Once inside, he grabbed the microphone from the prince, and launched into his routine. He later said he never expected to make it in, but that security was "non-existent".

It was regarded as the worst incident of its kind since 1982 when Michael Fagan found his way into the Queen's bedroom at Buckingham Palace.

Mr Barschak said he was shocked and surprised by yesterday's announcement. His mother, Miriam Barschak, of Kilburn, north London, added: "It's wonderful. That is all we are going to say about it."