House of Commons
During the Iraq war debate in the Commons, former Conservative Chancellor and leadership contender, Kenneth Clarke, spoke out against the party line.
He insisted that the case had not yet been proven to go to war with Iraq.
Mr Clarke was one of 13 Conservative MPs to defy the party's leader, Iain Duncan Smith, and vote in favour of a Labour rebel amendment seeking to delay military action in Iraq.
The amendment, tabled by MP Chris Smith, proposed that Britain should pursue peace through the United Nations and give Saddam Hussein more time to comply and disarm.
More damaging for Tony Blair, however, was the 121 Labour rebels who broke a three-line whip to vote against the government in favour of the amendment.
The biggest backbench rebellion of his premiership, it was a damaging blow to Mr Blair's authority and portrayed the leader as isolated within his party.
A further 54 Labour rebels voted against the government's own motion which followed, calling on Iraq to recognise its "final opportunity to comply".
The rebel amendment was defeated and the government's motion comfortably passed.
Although neither would determine whether Britain would go to war, the sheer scale of the rebellion highlighted just how divided the House was over going to war with Iraq.