Theresa May’s pledge to go before the second stage of the Brexit negotiation if her deal passes, is already reaping some rewards. Boris Johnson has told a meeting of the ERG that he is now backing the deal. His argument is that what is going on in Parliament means there is a real chance of losing Brexit and that a change of personnel will lead to a change of policy in stage two. This addresses his concern that Theresa May would interpret the withdrawal agreement passing as a license to go and negotiate a Chequers-style agreement.

Boris Johnson isn’t the only big beast shifting tonight. Iain Duncan Smith, who played a crucial role in persuading May to make this offer, has also said he will now back it. Charlie Elphicke, the secretary of the ERG, has also swung in.

Attention now shifts to Dominic Raab and Steve Baker, the two biggest names holding out. Baker has been digging in over the last few days, and it would be a surprise if he came over. Raab is a more interesting case. He did resign as Brexit Secretary over this deal. But some of the concerns he raised at that time have now been addressed. He also has leadership ambitions and it is hard to see how someone could unite the party if they were to carry on opposing this deal even as the vast majority of Tory MPs swing behind it, albeit without much enthusiasm.