from Wednesday, the first day of Johnson’s premiership, Sky’s chief executive, Jeremy Darroch, said in an email to staff.

Griffith is expected to stand down from Sky while working for Johnson. The former Rothschild investment banker joined Sky in 1999, and became finance chief for the group in 2008.

He was a key part of the team during the attempted takeover of Sky by Rupert Murdoch’s 21st Century Fox, when Murdoch’s son James was chairman of the broadcaster.

Johnson, who is expected to enter No 10 next week, has been spending up to 13 hours a day at Griffith’s lavish £9.5m townhouse, with sources on his team saying he has switched his focus towards strategy for government.

A Johnson campaign source said Griffith had kindly opened up his home to let membersof the transition team meet there, but the businessman was not part of that operation.

Griffith received about £17m after Sky was acquired by Comcast, which needed to buy out some of the stakes and share schemes held by Griffith and other staff in the group.

He ran as a Tory parliamentary candidate for Corby in 2001 and 2005. He lost both times to Labour.

Munira Mirza during her time as Johnson’s deputy mayor for education and culture. Photograph: Mary Turner/Getty Images

Mirza, whose family came to the UK from Pakistan, criticised the Labour MP David Lammy’s 2017 review of racism in the criminal justice system, which was commissioned by David Cameron and supported by May.

She said it was an example of how “astonishingly, it seems that a lot of people in