Theresa May has been told she could be ousted like Margaret Thatcher unless she sacks her chief Brexit negotiator, Oliver Robbins, and ditches his plan to bind Britain into a customs partnership with the EU.

David Davis, the Brexit secretary, has told May that she should ignore Robbins and start listening to her ministers instead — a move that the mandarin has interpreted as an attempt to get him fired.

Davis also staged a showdown with May’s chief of staff, Gavin Barwell, last weekend, after The Sunday Times revealed that her aides had “war-gamed” whether he would resign if the UK stayed in a customs union with Brussels.

Pro-Brexit business leaders have demanded Oliver Robbins be sacked AIDAN TAYLOR/OPEN GOVERNMENT LICENCE

In what amounts to the most perilous moment for May’s premiership this year, a close friend of