Penny Mordaunt has been promoted to the cabinet as the new International Development Secretary, following the resignation of Priti Patel.
Like Ms Patel, Ms Mordaunt was among Conservatives who backed Leave during the EU Referendum campaign.
The former work and pensions minister, 44, has now left Downing Street and arrived at her new department.
Ms Patel quit on Wednesday, admitting unauthorised meetings with Israeli officials had “lacked transparency”.
It was the second cabinet resignation in a week. Last week Gavin Williamson replaced Sir Michael Fallon as defence secretary, after he quit saying his conduct had “fallen short” of the required standards after allegations of inappropriate sexual behaviour.