Theresa May is on Wednesday expected to be told she will face a “vote of no confidence” among Conservative MPs after the intervention of a senior former Cabinet minister, The Telegraph can disclose.

Owen Paterson, a former Northern Ireland and Environment Secretary who backed leave in the referendum, on Tuesday night wrote to Sir Graham Brady, the chairman of the 1922 committee of Conservative MPs, formally stating he had lost confidence in the Prime Minister.

There was growing speculation that Sir Graham had now received the 48 letters required to trigger a vote, which is expected to lead to a full-scale leadership contest in the coming weeks.

The BBC reported that the 1922 committee chairman has requested to see Mrs May after Prime Minister’s questions at lunchtime on Wednesday. She will meet with her Cabinet in the morning amid calls from some Tory MPs for senior ministers to intervene and replace her with a caretaker leader before a formal vote is called.

The Telegraph has published Mr Paterson’s letter to Sir Graham Brady, the chairman of the 1922 committee of Tory MPs, in which he says Mrs May is a “blockage” to a clean Brexit.