Campaigner 'on Palace balcony'
A Fathers 4 Justice campaigner dressed as Batman is protesting at Buckingham Palace, the group has said.
Jason Hatch, 33, entered the grounds and scaled a wall onto a balcony, said group spokesman Matt O'Connor.
He said the incident was to highlight the court appearance of Patrick Davis, who allegedly staged a flour-throwing protest in the Commons.
Metropolitan Police have cordoned off the area as crowds built up to watch the protest.
I'm not sure where he is but I can hear him shouting
Buckingham Palace spokeswoman
Mr O'Connor said: "We've got a guy dressed as Batman who's on Buckingham Palace on a balcony. He legged it past the armed guards."
The protester, standing on a ledge to the right hand side of the main balcony at the front of the palace, unfurled a banner which read: "Super dads of fathers 4 justice".
Also on the banner are the words: "Fighting for your right to your kids".
A Buckingham 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 was not at the Palace as she is at Balmoral in Scotland, the spokeswoman added.
Comedian trespass
John O'Connor, a former Scotland Yard Flying Squad commander, said it was an "absolute disgrace".
"They are more concerned about the changing of the guard and all the ceremonies than taking security seriously. No-one there seems to have the ability to stop intruders," he told BBC News 24.
A report was published a year ago into the breach of security during Prince William's 21st birthday party.
Comedian Aaron Barschak set off six alarms and appeared on CCTV several times without sparking a response when he gatecrashed the party at Windsor Castle, it found.
http://news.bbc.co.uk/2/hi/uk_news/3652502.stm