Philip Hammond has resigned from the government as Boris Johnson prepares to begin appointing his new cabinet.
Johnson was formally appointed prime minister on Wednesday afternoon after meeting the Queen at Buckingham Palace.
International Development Secretary Rory Stewart and Justice Secretary David Gauke has also quit. As has David Lidington, the de facto deputy prime minister, announced he will leave the government.
In her final speech in Downing Street, Theresa May said she hoped that young girls seeing a female prime minister would realise “there are no limits to what you can achieve”.
Johnson, after being appointed PM, will deliver a speech on the steps of No.10 before firing ministers he no longer wants in post and appointing replacements.
Home Secretary Sajid Javid and Treasury Chief Secretary Liz Truss have been touted as possible replacements for Hammond.
Dominic Cummings, who ran the Vote Leave campaign, is said to be being given a senior adviser role in No.10.
Johnson will also have to decide what to do with Jeremy Hunt, his rival for the leadership, who has reportedly resisted attempts to demote him.
The new cabinet is expected to include a recall to the cabinet for Priti Patel, an ardent Brexiteer who was forced by May to resign as international development secretary over unauthorised contacts with Israeli officials.
The Times reported that she was in line for the post of home secretary in the new administration.
Health Secretary Matt Hancock, who threw his weight behind Johnson after dropping out of the leadership race himself, is expected to be handed a top role.
Former Brexit Secretary Dominic Raab and leading eurosceptic backbencher Jacob Rees-Mogg have also been tipped for senior posts.
A source close to Johnson said: “Boris will build a cabinet showcasing all the talents within the party that truly reflect modern Britain.”
It is likely to mean a promotion for Employment Minister Alok Sharma, who is expected to take his place around the top table.
Unlike Patel, he voted Remain in the 2016 referendum but was quick to declare his support for Johnson when he threw his hat into ring following May’s decision to resign.
Among the more junior ministerial ranks, he was said to be looking to bring on rising talent, with promotions expected for Local Government Minister Rishi Sunak, Cabinet Office Minister Oliver Dowden and Treasury Minister Robert Jenrick.
There is also expected to be a return to government for Tracey Crouch who quit last year as sports minister after clashing with the Treasury over delays to a crackdown on fixed-odds betting machines.