May's office flagged Monday's events as "a refresh" of her top team.
May even posted a photo on her social media site showing her alongside a line-up of all-female MPs appointed to roles in the party whip's office. May was said to be "disappointed" at losing Greening, who opposed Brexit, and could now vote with pro-European Union rebels in the House of Commons.
Her sacking seems to be harsh in the extreme.
As Mrs May turned her attention to junior ministerial roles on Tuesday, she faced calls to be more courageous in bringing about change and diversity to refresh the look of the Government.
But the reshuffle was thrown into confusion nearly immediately when an official tweet announced Chris Grayling as the new Conservative Party chairman.
"I'll continue to work outside of government to do everything I can to create a country for the first time that has equality of opportunity for young people wherever they are growing up".
Greening, who saw her majority in the London constituency of Putney cut from 10,180 to 1,554 in last June's election, may have concluded that she had a better chance of retaining her seat from the backbenches.
But the former justice secretary has not been given the title of First Secretary of State, which marked Mr Green out as Theresa May's effective deputy. The idea had been to inject momentum in her domestic policies and show she was not just "Madam Brexit", but a leader with a shot at re-election in 2022.
Grayling remained transport secretary. Instead, Esther McVey becomes Work and Pensions Secretary.
Pakistan army chief: United States general called, offered assurances
In his tweet on January 1, Trump had lashed out Pakistan, accusing the country of "lying and deceit" in return for billions of dollars.
SpaceX customer blames Northrop Grumman for missing satellite
The Falcon 9 with Zuma kicked off on 8 January 2018 to 04:00 Moscow time from the cosmodrome on Cape Canaveral. SpaceX denied providing any comment related to the mission as it contained confidential information.
President Trump clarifies position on FISA after tweet expressing surveillance concerns
Democrats tried to use the confusion as a way to postpone the vote but Republicans pressed ahead and conducted business as usual. But civil liberties groups are anxious about two controversial practices that could compromise the privacy of Americans.
There were some surprising developments, unrelated to the planned reshuffle.
Earlier on Monday, Northern Ireland Secretary James Brokenshire resigned from the Cabinet due to a lung condition requiring surgery. Karen Bradley, another colleague she knows and trusts from her own past experience, was appointed to replace him.
Making sure the scales didn't tip in favor of either side of Brexit was a handicap.
Justine Greening, formerly education secretary, has quit government after being offered the Department of Work and Pensions, according to multiple reports, replaced by Damien Hinds.
It was later confirmed that Brandon Lewis, formerly immigration minister, was the new party chairman.
Justine was a cabinet minister who was passionate about her brief, and truly believed in the importance of apprentices to the economy, and for the social mobility of young people through the acquisition of a skilled trade. "And if you can move them on after six months, all the better", the former minister said. He then added a hashtag urging May to "get it right".
The health secretary Jeremy Hunt, under pressure over a winter NHS crisis, refused to budge when he was asked to become business secretary, which is effectively a demotion.
Sacked Education Secretary Justine Greening (ringed right) immediately joined the group of Tory remain rebels today during the first PMQs since the reshuffle.
David Lidington replaced Mr Green, taking his other title as Cabinet Office Minister, while Brandon Lewis was installed to take over from Sir Patrick McLoughlin as Conservative Party chairman.