She was appointed, seemingly from nowhere, to a senior Cabinet positions in the December 2004 reshuffle triggered by David Blunkett's first resignation.
Last week, she was moved to the newly-created role of community and local government secretary. In the intervening 17 months, the 38-year-old struggled to live up to her billing as one of the Government's most talented rising stars.
Her number two, Jacqui Smith, has also left the department. The ex-teacher's competent spell as schools minister led to a promotion to chief whip.
Within days of landing the education job, the mother-of-four was the subject of vicious briefing to the press from fellow female MPs. Then it was Ms Kelly's membership of the Roman Catholic Opus Dei movement that dogged her. The lurid account of the ultra-conservative group in Dan Brown's best selling Da Vinci Code encouraged speculation over whether the new Education Secretary wore a spiked garter.
By the time she had lanced the media boil by admitting her links to the group, doubts about Ms Kelly had begun to surface in the education community.
Suspicions that she had been appointed - with the upcoming general election in mind - to focus on parent power rather than teachers were borne out in her first education speech in Manchester, in January 2005.
At the North of England education conference, she used the P word no fewer than 44 times in as many minutes, compared with just six mentions of teachers.
Later, her decision to ignore much of the Tomlinson report on reform of secondary education put her at odds with the majority of the education community. As a result, she received a rough ride at the Secondary Heads Association conference in March 2005.
The following month she was dubbed "Calamity Jane" by John White, president of the National Association of Head Teachers. There was worse to come in May. Andrew Adonis, Mr Blair's schools guru, became junior education minister, in a move widely seen to undermine Ms Kelly.
The open revolt among Labour MPs against the education Bill, added to her woes. But it was the scandal over sex offenders teaching in schools in January that probably did for Ms Kelly.
In her worst fortnight, the media scented blood and criticised not only her ability, but her hairstyle, voice and dress in a series of very personal attacks.
A make-or-break Commons speech seemed to have saved her skin. But for Mr Blair it was obviously too little too late.