The highly anticipated vote on UK Prime Minister Boris Johnson's Brexit deal has been postponed after parliament passed the Letwin amendment, delaying approval of the legislation. 

The amendment, suggested by Conservative MP Sir Oliver Letwin, withholds parliamentary approval for the deal until all the relevant legislation implementing the UK's withdrawal has become law. It passed by 322 votes to 306. 

Johnson said the "opportunity to have a meaningful vote has been passed up," but that he refused to be "daunted or dismayed" in his attempts to pass his deal into law. Even so, he promptly decided to cancel the main vote on his deal, sending MPs home without voting on it. The government expects MPs to vote on the crucial legislation in the coming week, perhaps as early as Tuesday. 

Before then, political observers will be fascinated to see if Johnson contacts the EU. Under the terms of the Benn Act, which kicks in at 23:00 local time on Saturday, the government is obliged to write a letter to Brussels requesting a delay to the UK's exit from the EU. However, Johnson said in parliament: "I will not negotiate a delay, nor does the law force me to."