London | British Prime Minister Theresa May has suffered another resounding defeat over her Brexit deal, losing the parliamentary vote by 391 votes to 242 - dealing a further blow to her authority and deepening the country's economic and political uncertainty.

The scale of the defeat, a margin of 149 against the Brexit plan she'd agreed with the European Union, has left Mrs May with no immediate way of pressing ahead with her deal. So she immediately conceded that she would have to move to a parliamentary vote on a no-deal Brexit, scheduled for Thursday morning (AEDT).