Theresa May’s Brexit difficulties will continue as she faces a grilling by MPs about her plans for leaving the European Union.

The Prime Minister avoided a damaging defeat – which could have had major implications for her leadership – by just six votes in the Commons on Tuesday night.

She now faces a potentially difficult session of Prime Minister’s Questions and an appearance in front of the Liaison Committee of senior MPs on Wednesday.

Mrs May will also try to rally her deeply divided Parliamentary party as she addresses a meeting of the 1922 Committee of backbenchers.

Pressure on the Prime Minister continued to mount as a poll gave Labour a five-point lead over the Conservatives.

On a night of high drama in Westminster on Tuesday, the Prime Minister thwarted a rebel Tory move which could have forced her to try to keep Britain in a customs union with the EU by 307 votes to 301, helped by Labour Brexiteers.

But 12 Conservatives broke ranks to back the customs union measure, even though Tory whips told would-be rebels that there would be a confidence vote if it passed – potentially resulting in the collapse of Mrs May’s administration.

Mrs May was defeated on a separate amendment to her flagship Trade Bill, which will require her to seek continued UK participation in the EU’s system for regulation of medicines after Brexit.

Leading Tory Remainer Anna Soubry called for a government of national unity to deal with Brexit made up of Plaid Cymru, the SNP and “other sensible, pragmatic” MPs.

She told BBC Radio 4’s Today programme: “We simply cannot go on like this.”

Ms Soubry said the whipping operation during Brexit votes on Tuesday evening had been an “appalling spectacle”.

“These nonsenses of threatening general elections and votes of confidence in the Prime Minister and as I actually said to the deputy chief whip ‘bring it on’ because I shall be the first in the queue to give my vote of full confidence in the Prime Minister,” she said.

“Problem is, I don’t think that she’s in charge anymore. I’ve no doubt Jacob Rees-Mogg is running our country.”

And Tory chairman Brandon Lewis came under fire for taking part in the two crunch votes despite being “paired” with Liberal Democrat deputy leader Jo Swinson, who is on maternity leave – an agreement meaning he should have sat out the divisions.

He apologised, claiming it was an “honest mistake” made by the Tory whips in “fast-moving circumstances”, but Ms Swinson said it was deliberate “cheating”.

Theresa May avoided defeat over a customs union by a margin of 307-301 (parliamentlive.tv)

While Mrs May faces a session in front of the Liaison Committee, made up of senior MPs who chair Commons select committees, a debate will take place in the main chamber on the future relationship between the UK and EU.

There has been speculation in Westminster that Boris Johnson could take the opportunity to make a statement following his resignation as foreign secretary over the Chequers Brexit plan.

Such a statement would have echoes of Geoffrey Howe’s devastating resignation speech after quitting Margaret Thatcher’s Cabinet in a row over Europe – an intervention which contributed to her being toppled within weeks.

An indication of how precarious Mrs May’s position is came in a YouGov poll for the Times, which put the Conservatives on 36% – down one point from last week –  behind Labour on 41%, up two points.

:: The YouGov poll of 1,657 British adults was conducted on July 16 and 17.