Prime Minister David Cameron faced the biggest test of his authority yet Monday night as 81 of his own backbenchers rebelled against the three-line whip by voting for a motion to hold a referendum on Britain's future relationship with the EU.
The number of Tory rebels reflected the top-end estimate of MPs who were rumoured to vote against the government and against Cameron's wishes. It is the biggest Conservative revolt since the days of John Major, who faced a rebellion of 41 over another issue on the EU.
Although Cameron technically won the day with a majority of 372, the high number of rebel voters and bitterness among the other MPs that were forced to vote with the government will ensure that Europe will remain on the party and political agenda for several years to come.
In a further developments, Downing Street was shocked when an aide to the Europe minister, Adam Holloway, resigned from the government. He said: "I'm not now prepared to go back on my words to my constituents and I'm really staggered that loyal people like me have actually been put in this position. If Britain's future as an independent country is not a proper matter for a referendum, then I have absolutely no idea what is."
The private parliamentary secretary to the Northern Ireland secretary, Stewart Jackson, also resigned.
Two polls from different sources published prior to the vote, which showed that if there were a referendum tomorrow there would be huge support for withdrawing from the EU altogether, which only fuelled subsequent debate.
Commons Vote on EU Referendum
For: 111 - Against: 483 (Majority: 372)