Johnson appoints ex-Treasury official as No 10 chief of staff

Boris Johnson has appointed a new chief of staff (Yui Mok/PA)

Boris Johnson has appointed a former Treasury official as his Downing Street chief of staff.

Dan Rosenfield will begin working in No 10 next month before he formally takes over from acting chief of staff, Edward Udny-Lister, in the new year, Downing Street said.