While Brexit divisions have restricted her options, she is looking to make her Conservative government more representative of Britain by promoting more women, people from ethnic minorities and recently elected lawmakers to leadership positions. And it may be the harbinger of future political troubles for Mrs May.
The Conservatives posted a message announcing that Chris Grayling was replacing Sir Patrick McLoughlin - but seconds later they erased their congratulations for the Transport Secretary.
Garnier was subject to an internal investigation late past year after asking his then secretary to buy sex toys, but was cleared of misconduct.
No 10 sources insisted the incident had nothing to do with his departure.
She moves from her previous role as the UK Secretary for Digital, Culture, Media and Sport.
Conservative MP Philip Davies told The Daily Telegraph newspaper: "It certainly does not do anyone any favours to promote people who are not ready for promotion just due to their gender or race".
In a letter to the prime minister, McLoughlin said he felt it was the right time to leave the Cabinet "as we discussed some months ago".
The most powerful ministers remained in place, and Education Secretary Justine Greening quit the government after refusing to move to a new post. She hoped to showcase a fresh generation of Tory talent; shake up the party election-fighting machinery that misfired so badly previous year; and show her determination to get to grips with domestic challenges that have been all but overshadowed by Brexit for the past 12 months.
"It should come as no surprise that the European Union is also preparing for this possibility", Pat McFadden, a Labour member of the parliamentary Brexit committee said.
In: The position previously held by the ill-fated Damian Green goes to David Lidington who moves from the justice ministry.
Health Secretary Jeremy Hunt has been tipped as a possible replacement.
Steve Baker, a long-standing Eurosceptic MP and now a junior minister in David Davis's department, is thought to be the current favourite.
On Ms Greening's resignation, the spokesman said: "She has displayed a clear commitment and passion for equality and social mobility and improving the opportunities available to children across the country". Mrs May's inability to impose her will on her ministers and the failure of her advisers to prepare the ground adequately for the reshuffle will do nothing to enhance her claim to competence.
The way she left the government could cause a headache for the PM when the Putney MP, who backed Remain in the referendum campaign, returns to the back benches.
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