Boris Johnson has warned his cabinet that it is “time for the slaughtering of sacred cows” as he vowed to cull the pet projects of his predecessors Theresa May and David Cameron.

Ministers were ordered yesterday to go through their spending line by line and send the Treasury suggestions for projects that could be cut or abandoned entirely.

The prime minister said that they should push ahead with the cuts even though some officials would “squeal” and others would behave “like a tiger protecting its cubs”. The time had come for “tough decisions”, he said.

It is understood that hundreds of legacy projects, some dating back to the coalition government under Mr Cameron, could come under review. No specific projects were discussed at the cabinet