The Respect MP missed the division on Wednesday which saw Tony Blair's majority plunge to just one because he was in Ireland for a performance of his one-man show.
Vincent Cable, the Liberal Democrat Treasury spokesman, also missed the division, because he had left the building to speak to constituents lobbying Parliament to press for Third World trade reform.
Had they been in the division lobbies at 3.58pm their votes would have defeated the Labour Government for the first time since 1997 and plunged Mr Blair's premiership into crisis.
While MPs were poring over the Terrorism Bill line by line in the Commons, Mr Galloway was preparing to appear at the Everyman Palace Theatre, Cork. Theatre-goers paid up to €23 (£15.50) to see An Audience with George Galloway MP, billed as a chance to "ask about his beliefs and passions".
A spokesman for the MP, who defeated the Blairite Oona King in a bitter election battle, said he was a fierce critic of the terrorism legislation. He said: "This is a small party trying to reach out as widely as it can. It is not just about being inside the Westminster bubble.
"The Bill will go to the Lords and will be blown out of the water and come back to the Commons. When the crucial vote comes, George will vote against it."
Mr Cable said he was furious that he had to leave the Palace of Westminster to see his constituents because of the security logjam caused by people lobbying their MPs in favour of the Make Poverty History campaign. He ran back to catch the vote, but was too late.
He said: "I was in Parliament and I was eager to vote. I was just caught up - as other members were - in the appalling problems of security surrounding the lobby of Parliament. I went to see [constituents] on Victoria Embankment. They were very annoyed and I stayed and talked to them."
Earlier this year, the Government survived a division on the Prevention of Terrorism Bill when 17 Liberal Democrats, including the leader, Charles Kennedy, failed to appear. The Chief Whip, Andrew Stunell, said a defeat for the Government would have been a "nice technical knock-out". He added: "What it did do is show the Government that it had no chance with the most important and the most controversial part of the legislation."
Austin Mitchell, Labour MP for Great Grimsby and a member of the Socialist Campaign Group of MPs, abstained on the key vote. He said: "The problem was nobody expected that vote to be that close."
Another left-winger, Paul Flynn, Labour MP for Newport West, voted with the Government. He said: "I have been wrestling with the idea that I saved the Government.
"I don't want to see the Government humiliated. I want them to have a warning shot across the bows."
Nine Tories missed the vote, including the deputy leader, Michael Ancram, who was in Washington. Other missing Tories were on parliamentary business abroad, at funerals, in hospital or on jury service. Alan Beith, the Liberal Democrat MP for Berwick-upon-Tweed, was at a funeral.
MPs who did not vote
Deputy leader of the Tories. In Washington for a long-arranged meeting with George Bush's staff.
Liberal Democrat MP for Berwick-upon-Tweed.
Spent the day in Northumbria for a funeral. Rushed back to Westminster after the event, but arrived after crucial votes.
Conservative MP for Northampton South. Reason unknown
Conservative MP for Chelmsford West. Abroad on a parliamentary delegation.
Liberal Democrat Treasury spokesman. Left the Commons to talk to constituents lobbying Parliament for Make Poverty History campaign. Did not get back into the Commons for the vital vote.
Conservative MP for Bournemouth East. Abroad on a parliamentary delegation to South Africa.
Respect MP for Bethnal Green and Bow. Appearing in a one-man show in Cork.
Conservative MP for Bury St Edmunds. Jury service.
Conservative MP for Mid Sussex. In hospital.
Conservative MP for Upminster. Abroad on parliamentary delegation.
Conservative MP for Congleton. Attended funeral.
SIR NICHOLAS WINTERTON
Conservative MP for Macclesfield. Attended funeral.Reuse content