A Liberal Democrat MP has resigned the party whip so he can support Theresa May’s Brexit deal.

Stephen Lloyd said he was “genuinely saddened” over the decision, but had promised his constituents that he would support the deal the Prime Minister brought back from the EU.

And he said he had pledged to not back calls for a second referendum – a key Lib Dem policy.

In his resignation letter to Lib Dem chief whip Alistair Carmichael, the Eastbourne MP wrote: “I appreciate me voting this way and not supporting a People’s Vote are counter to the Liberal Democrats’ formal position.

“Consequently, I have decided the only honourable thing for me to do is to resign the party whip in Parliament.”

He said he would continue to “fight hard for liberal values””and remain a member of the party, saying he has “nothing but respect and affection” for Lib Dem leader Sir Vince Cable.

Mr Carmichael said in his reply that Mr Lloyd was right that it is a “touchstone issue for the party and it is impossible to reconcile your position with that of the party”.

“I understand the reasons why you feel it necessary to take this step and know the strength of your conviction that this is a necessary thing for you to do. With regret, therefore, I accept your resignation.”

The news of an extra vote for Mrs May’s Brexit deal will no doubt be welcomed inside Number 10, as support among MPs is flagging ahead of a crunch Commons vote next Tuesday.

But it lowers the number of Lib Dems in the Commons to 11, as MPs sitting as Independent increases to nine.

A Liberal Democrats spokesman said: “We respect what we know was a difficult decision for Stephen ahead of next week’s vote and are sorry to see him go. Liberal Democrats are clear that we will be voting against Theresa May’s deal.

“The Liberal Democrats have campaigned for an exit from Brexit and a People’s Vote where people can choose to remain in the European Union since the referendum was held. We will continue to fight for this in Parliament.”