Parliament's past security breaches

Police have arrested one person after an incident in Parliament involving guests at a party hosted by Conservative chairman Eric Pickles. They became locked in a fracas and trespassed beyond their security clearance.

It is the latest in a long line of security breaches at Parliament, here are a handful of the most recent high-profile ones.

AIRPORT PROTEST

The protesters said they got up via a fire escape

February 2008:

Six protesters against the expansion of Heathrow Airport climbed on to the roof of the Houses of Parliament, unfurling banners and throwing paper planes. They said they got up there by way of a fire escape, but police said there was a strong possibility they were guests of security pass holders.

TRIDENT ANGER

Greenpeace hoped to persuade MPs not to back a renewal of Trident

March 2007:

Four Greenpeace campaigners scaled a crane beside the Houses of Parliament in protest at the government's plans to update its Trident nuclear weapons system. They went on to unfurl a 50ft banner reading "Tony heart WMD" ahead of a Commons vote on the issue. MPs eventually voted to back the plans, despite the biggest revolt by Labour MPs since Iraq. The company which had been using the crane to carry out repair work on Westminster Bridge described the protest as a "real pain".

COMMONS INVASION

Protesters entered the chamber where MPs were debating the bill

September 2004:

Parliament was suspended after five protesters got into the Commons chamber while MPs debated whether to ban hunting with dogs. The men got in dressed in boiler suits and posing as builders, before discarding their suits to reveal foxhunting protest T-shirts, while thousands of people protested outside. When the Commons resumed business, MPs voted to back the ban. Protester Otis Ferry, son of musician Bryan Ferry, was among eight men convicted of violating the Public Order Act over the protest and received 18-month conditional discharges.

PURPLE FLOUR

Dyed flour was thrown at Tony Blair in the House of Commons

May 2004:

During prime minister's questions Tony Blair was hit by a condom filled with purple flour thrown by campaigners from the pressure group Fathers 4 Justice, weeks after a £600,000 new security screen had been installed in the chamber. Two men, Ron Davis and Guy Harrison had got in using tickets won at a charity auction. Mr Davis was convicted of disorderly behaviour and given a conditional discharge and fine, Mr Harrison was fined £600. It prompted a wide-ranging security review, led by MI5.