Like so many political storms, it seemed to come from nowhere.
On Sunday, January 8, as journalists focused on the merits of school choice and gay history lessons, a story buried on page five of the Observer revealed that the Education Secretary had approved a Norfolk school's appointment of a PE teacher who was also a registered sex offender.
The next day he was identified as Paul Reeve, who had been cautioned by police in 2003 for accessing websites containing child pornography. He had been given the job at Hewett high, Norwich, in December after a letter from Ruth Kelly, written in May, acknowledged his appearance on the sex offenders register but said the risks of his continued teaching "were acceptable".
Norfolk police, who had put Mr Reeve on the register, stepped in when they learned of his appointment. He was suspended after five days in the job and later resigned.
The news stunned children's charities and teaching unions. They were surprised that so little had been done after the Soham murders and subsequent Bichard inquiry highlighted the deficiencies in the system of checking records of school staff.
Sir Michael Bichard gave interviews saying he was disappointed that the recommendations of his inquiry had not been acted upon.
The Department for Education and Skills initially refused to comment on individual cases, but as the rest of the media picked up the story Ms Kelly said she would review what had happened and see if changes were necessary.
On Tuesday it was established that Mr Reeve may have been cleared by another minister acting in Ms Kelly's name.
Initially Stephen Twigg, conveniently the one junior education minister from the time of the letter no longer in Parliament, found his name in the frame and was forced to deny it was him.
Then on Wednesday, January 11, the crisis shifted up a notch as Ms Kelly confirmed what many already suspected - that there were other registered sex offenders who had not been banned from working in schools.
By now rumours were circulating in Westminster that Ms Kelly would be moved in an imminent cabinet reshuffle, forcing Number 10 to issue a statement of confidence in her. Later it was claimed she had had to beg Tony Blair to keep her job.
The admission of further cases sent the papers into overdrive with reports the following morning that at least 10 sex offenders were working in schools.
Ms Kelly was forced to make a statement in the Commons later that Thursday afternoon, promising the Government would confirm the exact number. She received support from Labour MPs, but that did little to stem the growing tide of criticism.
Pundits said her speech, in which she urged schools to treat police cautions the same way as convictions, had been confusing. One described it as the "worst ministerial performance of the new parliament".
Then, on Friday the 13th, the heat came off Ms Kelly momentarily as Kim Howells admitted he had cleared Mr Reeve while acting as duty minister during the May general election campaign.
The officials likely to have advised the former higher education minister would have been ultimately answerable to Sir David Normington, then DfES permanent secretary.
Sir David was promoted to the Home Office this month. He was also in charge at the department when a series of events, including a scandal over teachers' criminal record checks, led Estelle Morris to resign as Education Secretary. And he was still there the following year when the so-called "schools funding crisis" blew up. Charles Clarke's bulldozing, no nonsense approach allowed him to ride out that storm.
But by Monday more bad news and Ms Kelly's comparative lack of experience and political allies raised serious doubts about whether she could pull off the same trick.
Trevor Kavanagh, the Sun's respected political commentator, wrote: "Ruth Kelly is finished as Education Secretary... She will be axed because Tony Blair will not want to be seen as putting the career of a third-rate minister ahead of children's safety."
That day's papers also identified Keith Hudson and William Gibson as two further sex offenders who been allowed to work on schools.
For the Prime Minister, the furore could not have come at a worse time. Ms Kelly and her department have been paralysed just when she should have been shoring up support for the education Bill.
And as The TESS went to press the number of Labour backbenchers joining the rebel ranks opposing the bill reached 90.
Last night, Lord Kinnock, the former Labour leader, was due to join a platform with Lady Morris, former education secretary, and others who believe that trust schools, free from local authority control, will lead to unfair admission practices.
On Tuesday the Prime Minister's spokesman admitted a vote on the Bill may now be pushed back to March.
One embarrassing story that was almost buried by other events was the resignation of Des Smith, a head working as a consultant for the Specialist Schools and Academies Trust, who was caught saying honours would be offered to business people prepared to sponsor the Government's flagship education projects.
While Ms Kelly was not personally implicated, it gave an unsavoury whiff to the academies programme.
The Prime Minister said he had confidence in his Education Secretary and, as the furore continued, teachers' leaders came to her defence. But there was no escaping the fact that, in Ms Kelly's statement to Parliament yesterday, she needed to make the performance of her short political life.