Boris Johnson has rowed back on one of his four Brexit "red lines" after Theresa May confirmed the UK would be subject to European Court of Justice (ECJ) rulings during transition.
In response to a question by backbencher and arch Leaver Jacob Rees-Mogg, the Prime Minister this afternoon said an implementation period was necessary because of the need for a "smooth and orderly process of withdrawal, with minimum disruption".
She added: "We have to negotiate what will operate during that implementation period. And, yes, that may be that we will start of with the ECJ still governing rules for part of that period. But what we are also clear on is that we can bring forward discussions and agreements on issues like a dispute resolution mechanism and if we can bring forward [that] at an earlier stage, then we would wish to do so."
She stressed it was "highly unlikely" that any new laws would be brought in during that period that hadn't already been discussed "and on which we would have been able to say whether they would be a rule that we would sign up to, or a rule that we would not wish to sign up to".
However, she did not rule out the possibility that it might happen - something which Johnson said must absolutely not happen, in one of his recent interviews ahead of the party conference.
Rees-Mogg, who has been unwavering in his support of the Prime Minister, later told City A.M. he was not happy with this concession. "If the ECJ still has jurisdiction we will not have left the EU,he said. "It is perhaps the most important red line in ensuring the leave vote is honoured."
But the foreign secretary - who has been on thin ice since his "dead bodies" comment - has put a statement describing her speech as "great", echoing her view that the chances of new rules coming in were "very small".
He added: "Yes, we will have to mostly operate under existing rules during the transition but we will be able to negotiate proper free trade deals and business will be able to prepare properly for Brexit.
"What matters is the end state and our freedom to do things differently and better - and once again the PM sets out a powerful vision: out of the customs union, out of the single market, taking back full control... the future is bright. Let's keep calm and carry on leaving the EU."
Former justice minister and fellow Brexiteer Michael Gove also urged Leavers to rally behind May, tweeting: "Strong statement from PM on Brexit - let's be pragmatic over implementation to secure maximum freedom to diverge from EU in end state."