The prime minister's announcement that he will keep hundreds of criminals behind bars who would otherwise have been released early is one he has wanted to make for weeks.
Andy Burnham had already expanded the list of people ineligible for early release and had consistently said he wanted to go further.
What is not clear is exactly what has changed to allow him to do so.
Earlier this month, the Ministry of Justice warned that exempting any more prisoners risked "prisons reaching capacity and collapsing".
The prime minister himself previously said he had "pushed to the very limits of what is possible to do".
In his exclusive interview with BBC Breakfast, Burnham picked out the release of people on controversial indefinite sentences and the deportation of foreign criminals as measures that had made his latest intervention possible.
It is understood extra capacity will also be created by immediately beginning work to create new cells in existing prisons.
But none of these are short-term solutions.
Ending indefinite sentences will require new legislation, meaning it could be years before space is freed up.
Previous governments have struggled to quickly deport foreign offenders and there are not thought to be any new returns agreements with other countries.
Retrofitting prisons to create more cells is also expected to take months.
People in government concede that in the short-term, Burnham will only be able to follow through on today's announcement by making prisons even more full.
With the adult male prison estate already running at 98% capacity, it is a move that could worry some in the sector.
But in the end, the prime minister believed he simply had to act.
The extra exemptions Burnham has announced are being described within government as a "political decision".
That is not surprising given the intense pressure that had built up, especially around the potential for PC Andrew Harper's killers to be released early.
Burnham's inner circle are mindful that political misjudgements at the start of Sir Keir Starmer's premiership caused long-lasting damage.
They believe Sir Keir never recovered from early rows over freebies and winter fuel payments, and point to a lack of major mishaps in Burnham's first six weeks in office as evidence of a more slick political operation.
There was some surprise in Downing Street about how much media attention the issue of early release received over the summer.
That is one reason why the prime minister's aides are relishing the new parliamentary term, when news stories come along at a faster rate and so are less likely to linger in the headlines.
After the initial flip-flopping on whether the government would be able to exempt more prisoners, the mother of PC Harper told BBC Breakfast that the handling of the situation had been a "hash".
Government officials working on the plans have spoken to the families of victims, who made it clear they did not want the new measures to be dripped out in leaks to the media.
Instead it was decided one big announcement would be the neatest option.
It had seemed likely that would come in the form of a parliamentary statement on Tuesday from the justice secretary.
Instead, the prime minister decided to make the announcement himself in an interview with BBC Breakfast.
It is understood Burnham was mindful of mounting speculation and wanted to give victims and the public as much certainty at the earliest possible opportunity.
In doing so, he may have risked the ire of the Speaker Sir Lindsay Hoyle, who is generally disdainful of governments that make major announcements outside of Parliament.
He may also have offered up ammunition to the Conservative leader Kemi Badenoch, who has already accused Burnham of being a "people pleaser" who finds it difficult to say no to people.
That characterisation is likely to be tested again when more stories inevitably appear about the victims of prisoners who will still be released early.
While this is not the first time Burnham has said he has pushed the system to the limit, Whitehall sources are now adamant there will be no more additional exemptions.
