Royal security was under fresh scrutiny today after a Fathers 4 Justice campaigner dressed as Batman staged a protest on a balcony at Buckingham Palace.
Jason Hatch, 33, from Gloucester, managed to reach the royal residence despite the presence of armed guards, the group claimed. Matt O'Connor, a spokesman for the organisation, said: "We've got a guy dressed as Batman who is on Buckingham Palace on a balcony. He legged it past the armed guards."
The home secretary, David Blunkett, is expected to make a statement in the House of Commons at around 10pm tonight regarding the security breach.
As Mr Hatch carried out his protest, a palace spokeswoman said: "There's a man there but it's a police matter. I'm not sure where he is but I can hear him shouting."
The Queen is currently on her summer break at Balmoral, in Scotland. "We've got no members of the royal family in residence," the palace spokeswoman said.
The protester, standing on a ledge to the right of the main balcony at the front of the palace, unfurled a banner that read: "Super dads of Fathers 4 Justice".
A policeman on the balcony to the left of the protester appeared to be talking to him. Another two men stood on the balcony. Police cordoned off the area immediately in front of the palace and a crowd gathered to watch on the Queen Victoria memorial.
Today's incident came during the summer opening of the palace to the public. A passerby said she had seen the man climb up the building at the far right of the palace and make his way across the front of it.
At one point he unfurled the banner in front of a window and someone inside tried to rip it down before he moved on to his current position. Two other intruders ran off after helping the demonstrator penetrate the palace grounds. Police said the men had been detected by security cameras as they used ladders to scale palace railings on Constitution Hill.
John O'Connor, a former Scotland Yard Flying Squad commander, said he was "astonished" that anyone had been able to breach palace security. "They are more concerned about the changing of the guard than taking security seriously," he told BBC News 24.
Dickie Arbiter, a former royal press officer, said officials in charge of security at the palace "are going to have to go back to the drawing board".
Royal security was reviewed after Ryan Parry, a Daily Mirror reporter, was able to get a job at Buckingham Palace as a servant before the US president, George Bush, stayed there during a state visit in November last year.
Stand-up comedian Aaron Barschak also highlighted lax security by gate-crashing Prince William's 21st birthday party at Windsor in June last year.
Fathers 4 Justice is notorious for its high-profile publicity stunts, and recently highlighted lax security at the House of Commons.
On Saturday, David Chick brought the London Eye to a standstill by climbing to the top dressed as Spider-Man. He was arrested after agreeing to come down, Scotland Yard said.