Police chiefs responsible for the security blunder at Windsor Castle were warned last night by David Blunkett, the Home Secretary, that their "heads are on the block" over the débâcle.
The criticism follows an apology to the Royal Family by Scotland Yard, which admitted that it was an "appalling breach of security" to allow a comedian dressed as Osama bin Laden to gatecrash Prince William's 21st birthday party.
The intruder, Aaron Barschak, 36, got in on Saturday night by scaling an embankment, climbing a tree, jumping on to a wall and reaching a terrace, the Metropolitan Police revealed. Once inside he was confronted by a person helping with the party and taken to a checkpoint, but officers failed to ask for a pass. He was arrested after he snatched the microphone from Prince William.
Mr Blunkett said he was "deeply concerned" by the security breach. Police gave him a six-page chronology of events leading up to the security breach yesterday. He will make a statement about the issue in the Commons today.
He said: "There is no question that ... everyone in every position all the way through counter-terrorism forces and royal protection know their heads are on the block ... I think we deserve better from those who are employed to look after our interests."
A disciplinary inquiry is also being undertaken into the actions of royal protection officers guarding the castle. Questions will also be asked about Commander Peter Loughborough, head of the 400-strong Royal and Diplomatic Protection Group. The Commander, who took over in February, is the 7th Earl of Rosslyn and the only hereditary peer in the police service.
Mr Barschak, a self-styled "comedy terrorist", said his stunt had been "unbelievably simple" and he was amazed he had got in. "I would rather security gets a big kick up the arse as a result of my actions than the whole thing just goes up in smoke," he said. "But Prince William is a lovely boy."
Mr Barschak described how guests had laughed at him as he took centre stage, before he kissed Prince William on each cheek and began to head towards the bar.
"The security was just non-existent", he told the Daily Mail. "I was carrying a bag which could have had a bomb in it. I was just yards away from the Queen and Prince Charles. If I had been a real terrorist, the entire Royal Family would have been wiped out."
He was bailed to return to a London police station next month.