Another Mr Johnson backer, Gavin Williamson, who was sacked by Mrs May over alleged Huawei leaks, is also thought to be returning.

Whitehall staff are reportedly anxious that Mr Williamson could be given another security sensitive role. He is tipped for Northern Ireland secretary or deputy PM.

The only confirmed role was chief whip, taken by Mark Spencer, a low-profile figure who has been in the whips‘ office for years.