But, two prison staffers told the BBC that governors were told to stop work on the implementation of the Sentencing Act two weeks ago. The government maintains there has been no decision to delay its introduction.

PC Harper's mother, Debbie Adlam, said the release of Jessie Cole and Albert Bowers - two of the passengers in the getaway car which killed Harper - was "sprung" on her family.

Cole and Bowers - who were 17 at the time - were sentenced to 13 years in custody for manslaughter but could be released after six years under the act.

The driver of the car, Henry Long - who was 18 - was jailed for 16 years for manslaughter but would not be eligible for early release.

"It just feels like another let down for Andrew really, when you look at the horrific way he was killed, we have to live with that," she told BBC Radio 4's Today Programme.

"The feeling that Andrew hasn't been given proper justice, it is very personal obviously... every victim will be feeling the same."

The Sentencing Act is the government's attempt to find a permanent, more sustainable solution to a prison overcrowding crisis after an emergency scheme was introduced by the Labour government in 2024.

Tens of thousands of inmates have already been let out of prison early under those measures.

Unlike the 2024 plan, the new act includes no exemptions for prisoners convicted of serious crimes, domestic abuse or terrorism.

Prime Minister Andy Burnham said on Wednesday he could not commit to changing the policy completely but would "look at it in detail before we go further forward".

He also acknowledged there was "pressure on prison places" and a failure to invest in the system created "an unacceptable situation".

Adlam said her message to Burnham was to "look at the big picture for the country".

"As a country you cannot have a justice system that works that way, just because it's full doesn't mean it's good enough to let people go, you need to find ways and I'd like to know what's being considered".

"I think the justice system has been lacking for quite some time and it needs a proper overhaul really."

Asked if the scheme will go ahead, Chief Secretary to the Treasury Emma Reynolds told the BBC: "That is something that he [Burnham] and the Justice Secretary will set out in the coming weeks."

"We do have to bear in mind, which I know is cold comfort to the victims, in 2024 when we took office, we inherited a system... that was on the brink of collapse, with fewer than 100 prison places available".