May's Brexit woes laid bare as Labour opposes move to fix exit date in law

The announcement by the Shadow Brexit Minister Paul Blomfield came amid reports that up to 20 Tory MPs are preparing to rebel on the amendment, warning that it could “tie our hands” in negotiations.

Speaking during tonight’s marathon debate in the Commons, the former Attorney General Dominic Grieve became one of the first backbenchers to confirm that he would not vote in favour of the motion, dismissing it as “mad”.

His act of defiance coincided with a warning from Mrs May’s own policy chief George Freeman that Britain risks becoming “an old people’s home that couldn’t pay for itself” if it fails to rise to the challenges ahead.

MPs have tabled almost 400 amendments to the EU Withdrawal Bill, with eight days set aside for debate between now and Christmas.

One of the most significant proposals is a Tory motion calling for a Parliamentary vote on the final Brexit deal which has gained substantial cross-party support.

The Government looks to have seen-off a potential rebellion by announcing that it will bring forward a separate Bill to implement the withdrawal agreement – thereby guaranteeing MPs a vote.

However, ministers are now facing a new challenge over their own amendment which aims to enshrine March 29 2019 as the official date of Britain’s exit from the EU.

Justifying the move yesterday, Brexit Minister Steve Baker suggested it was designed to reassure MPs about the scope of so-called Henry VII powers in the Bill. He stressed that the Government also wants to “provide certainty” for Eurosceptic MPs that there will be no attempts to delay the Brexit process.

But setting out Labour’s position, Mr Blomfield claimed that fixing the date was unnecessary and could threaten the chances of a smooth transition. In a separate statement, Shadow Brexit Secretary Keir Starmer urged Theresa May to withdraw the amendment and “stop pandering to the ‘no deal’ enthusiasts in her own party”.

According to reports in The Telegraph around 20 MPs have indicated they will rebel if the motion is put to a vote. Mr Grieve tonight confirmed he would not support the amendment as it would “fetter the Government’s own ability to carry out the negotiation”. He was joined in his criticism by the MP Ken Clarke, who described the amendment as “harmful to the national interest”.

The debate followed a speech by the chair of the Conservative Party policy forum in which he suggested the prospect of a bad Brexit “chills [him] to the bone”. Mr Freeman warned that the likely exodus of young people would turn the UK into “an old people’s home that can’t pay for itself”.