The Conservatives must start the process of selecting a new leader now, says a major party donor.

Alexander Temerko says Theresa May must be allowed to remain in post until Brexit has been delivered.

But he warns bad results for the party in next year’s local elections would trigger fresh leadership speculation.

He described Mrs May as a “good caretaker” but said she could not lead the party into the next general election.

“Therefore we must start the process of finding a new leader now and it is important to elect this leader by way of democratic vote with no coronation or other tricky methods,” he added.

He called for a new party chairman, to replace Sir Patrick McLoughlin, and co-chairmen to be elected by party members, a process which he said would allow potential leadership contenders to set out their credentials.