Insider suspected of worst security breach

A broken cardswipe machine was the weak spot that allowed pro-hunt demonstrators to achieve the most serious breach of Commons security in living memory. The fact that the Palace of Westminster currently resembles a building site also gave them cover for their audacious stunt.

A broken cardswipe machine was the weak spot that allowed pro-hunt demonstrators to achieve the most serious breach of Commons security in living memory. The fact that the Palace of Westminster currently resembles a building site also gave them cover for their audacious stunt.

Four months after Tony Blair was struck by purple flour hurled from the public gallery, a fundamental overhaul of the Commons security operation was inevitable last night.

There were also serious question marks over how the men got into the Palace of Westminster in the first place and, once inside, how they managed to negotiate the labyrinth of corridors and stairwells to reach the Commons chamber.

The group arrived in the Commons central lobby via the main St Stephen's entrance in the early afternoon, bearing what appears to have been a forged invitation to attend a select committee hearing.

They were possibly part of a wider group of pro-hunting activists who had an appointment with their constituency MP. Alternatively, they could have told police guarding the building they were on their way to one of the select committee hearings being held yesterday afternoon.

Police were investigating the theory that they were carrying a forged invitation to one of the meetings that they briefly attended. It was also suspected the men must have had some knowledge of the layout of the building.

The central lobby is the "crossroads" of the building, leading both to the Commons and Lords chambers, where generations of constituents have met their representatives. It is often a chaotic place thronged with politicians, their staff, party officials and members of the public.

A group of 10 chose to walk straight ahead, rather than towards the Commons or Lords, and found themselves in a small hall from which two flights of stairs lead to the committee corridor, which runs the length of the building. Members of the public have free access to the corridor, allowing them to attend the dozens of select committee hearings that are held every week. But to reach that point they have to pass at least two police checkpoints, begging the question of how they were allowed to proceed unchallenged, particularly when feelings were running so high outside the Commons.

There were suggestions last night that some of the men were dressed in suits and others in workmen's overalls to avoid raising suspicion when they turned left. A pile of discarded clothes was found in a corridor behind a door which should have been locked. The corridor is currently in chaos, with carpets rolled up and seats covered in plastic coating, as Westminster undergoes its annual refurbishment. To add to the confusion, hundreds of temporary contractors are currently on site.

The demonstrators should have come to a dead end when they reached the end of the corridor, which is blocked by a door that can only be opened by inserting a pass with a barcode into an electronic reader.

Crucially, however, the machine was not working, enabling them to open the door and descend two flights of stairs, bringing them within feet of the Commons chamber and ministers' private offices.

The group surged towards the Commons entrance behind the Speaker's chair where three members of the Serjeant-at-Arms office, dressed in the ancient regalia of their posts, were standing. By this stage they had discarded their "disguises" and were all wearing white

T-shirts bearing a black and white photograph. Four evaded capture, bursting into the chamber at 4.24pm through the "No" lobby door and shouting "our protest is peaceful" and "there is no democracy", before being wrestled to the ground by Commons staff. To add to the chaos, a fifth demonstrator then ran in through the doors of the members' lobby at the other end of the chamber.

With Labour MPs yelling at them to get out, Sylvia Heal, the Deputy Speaker, immediately ordered the suspension of the sitting as the five were dragged out of the chamber. The public gallery, already encased in a shield of plastic to prevent terrorist attack, was also cleared. As the protesters were being held in a small cell at the Commons, a security operation swung belatedly into operation.

The recriminations against the Serjeant-at-Arms department began immediately, with all three parties demanding an inquiry into the incident. One police officer said: "This is not our fault. We've been telling them for ages that security wasn't tight enough."

The Serjeant-at-Arms, Sir Michael Cummins, is due to retire at the end of the year. It looks certain that he will be the last head of Commons security to dress in breeches.