By Richard Wheeler and Elizabeth Arnold

AMENDING Brexit legislation to include Britain’s exit date from the European Union could be “positively harmful to the national interest”, a senior Tory has warned.

Former chancellor Ken Clarke said the Government’s amendment to the European Union (Withdrawal) Bill was “ridiculous and unnecessary”.

He said there would have to be a vote on the deal and legislation, which could take place after Brexit “particularly if the Government’s amendments are passed which increases that risk”.

As MPs discussed the Brexit date, the Father of the House said of the amendment: “It is not just ridiculous and unnecessary – it could be positively harmful to the national interest.”

Mr Clarke told MPs the amendment was introduced to allay concerns of Brexiteers, after Brexit Secretary David Davis said on Monday a Withdrawal Agreement and Implementation Bill would be brought forward if a deal was agreed with the EU.

Mr Clarke said: “But having made what might have been seen by some as a dreadful concession, a concession of all people to [Dominic Grieve] and [Anna Soubry] – shock horror: what kind of press was that going to produce, what kind of reaction from the fourth row ... behind me?

“So somebody is urged to bring something we can throw as a sop to the Foreign Secretary and the Environment Secretary and produce this ridiculous amendment.”

He was applauded by some Labour MPs as he concluded his speech.

His comments came after Labour’s Frank Field said ministers must follow Winston Churchill’s lead and create a “Brexit cabinet” while also ensuring exit day was according to British time.

Mr Field, who described himself as a “reluctant Brexiteer”, drew upon Britain’s Second World War experiences of different parties joining forces as he expressed disappointment with the Government’s strategy for EU withdrawal.

He has proposed including in the European Union (Withdrawal) Bill an exit date of March 30, 2019, an hour later than the Government’s amendment of 11pm on March 29, 2019. He said this represented “a little freedom” by ensuring the UK rather than the EU set the time for Brexit.

Deputy Speaker Lindsay Hoyle confirmed the provisional running order for the first two groups of amendments to the Bill, which has returned to the Commons so MPs can study it line by line at committee stage. The Bill seeks to transfer European law into British law.

Mr Davis’ Brexit day amendment – number 381 – can be debated but with any vote set for the eighth and final day of the committee stage, which will not be until next month at the earliest.

MPs will have to wait several weeks for a vote on the most contentious proposals.

Mr Field, opening committee stage, said: “My amendment decides on British time when to leave, their amendment is at the beckoning of Europeans.”

He added: “That’s our choice, it’s about the freedom, a little freedom, the beginnings of freedom that we hope will flow by actually setting us on the course of leaving the European Union.”

He later expressed his frustration with the Government’s strategy, noting he did not believe that there was a “sense of importance or drive or coherence” that Brexit merits.

Brexit minister Steve Baker said clause one in the Bill, which would repeal the European Communities Act 1972, would end one of the widest-ranging powers on the British statute book and make it unarguable sovereignty was with Parliament.

He called Mr Field’s amendment “technically deficient” given it did not set a specific time for Britain’s withdrawal, as he called on the Labour MP to withdraw it and support the Government.

Mr Baker added: “We recognise the importance of being crystal clear on the setting of exit day, and the Government is keen to provide the certainty that [Mr Field] and others are seeking.”

Tory former attorney general Mr Grieve told MPs no amount of “arm twisting” would make him vote for an amendment fixing exit date at 11pm on March 29.