A spanner in the works of Brexit for British Prime Minister Theresa May.

MPs have voted 309 to 305 to limit ministers’ power to make major changes to the law before Parliament has approved a Brexit deal.

UK correspondent Gavin Grey told Rachel Smalley the amendment would give them a legal guarantee of a vote on the final deal struck with Brussels.

He says a lot of people think this is going to weaken Theresa May's hand and make the deadline even tighter.

"It could embolden the remainers to now really try and cause havoc with the remainder of the course of the bill."

Theresa May is disappointed with the vote but is confident she's still on course to deliver Brexit.

LISTEN TO GAVIN GREY TALK WITH RACHEL SMALLEY ABOVE