Politicians have a duty to prevent the country committing "national suicide" in relation to Brexit, pro-EU Conservative MP Dominic Grieve has said.

Former attorney general and Beaconsfield MP told a packed hall that once Prime Minister Theresa May's deal is defeated in the Commons the only option is a second referendum.

He also said that Conservatives had "blown it" by letting a "revolutionary change take place in the name of tradition".

The Bucks MP was speaking at an "emergency convention" on a second EU referendum at Emmanuel Centre in Westminster on Friday.

Mr Grieve said that if MPs vote against Mrs May's deal as is predicted next week, then the only option is to go back to the British public and hold a second referendum.

He added: "My friend the Prime Minister has been doing her very best to try to find a way out of this problem that minimises the damage while trying to honour the referendum result.

"The unpleasant truth for her is that it can satisfy no one.

"There is only one way out. When the PM's deal is defeated, what else can we possibly offer to the British public which has any chance at all, but to go back to ask them to reconsider their decision.

"Parliamentarians do have some duties and one of them is to prevent people from committing national suicide."

Mr Grieve received a standing ovation from the packed hall when he stepped on stage and again when he finished speaking.

He told the audience that options such as a Norway-style deal or customs union with the EU just "brush problems under the carpet" and the only option was to go back to the public.

But Mr Grieve did not say what questions should be on a second referendum or whether a no-deal Brexit should be on the ballot paper.

Mr Grieve said he had told sixth form students that what it meant to be a conservative was to believe in principals of "continuity" and "pragmatism" and to try to avoid "revolutionary changes".

Mr Grieve added: "I then explained to them that we had blown it because we allowed a revolutionary change to take place in the name of tradition, and such things can never work.

"It ends up where you do not want to be."