PC Harper’s mother said all victims felt the same way when they were released from prison in the past.

But two prison staff told the BBC that governors had been told to stop work two weeks ago to implement the sentence. The government has said there is no decision to delay its entry.

PC Harper’s mother, Debbie Adlam, said the deaths of Jessie Cole and Albert Bowers – two of the passengers in the hit-and-run car that killed Harper – had “blown away” at her family.

Cole and Bowers – then 17 – were sentenced to 13 years in prison for manslaughter but could be released after six years.

The driver of the car, Henry Long – aged 18 – has been sentenced to 16 years for manslaughter but will not be eligible for early release.

He told BBC Radio 4’s Today programme: “You really get the feeling that Andrew is angry, when you see the horrible way he was killed, we have to live with that.”

“Andrew’s feeling that he wasn’t given proper justice, it’s clear that he’s personally … all the victims will feel the same way.”

The Sentencing Bill is the government’s attempt to find a permanent and sustainable solution to the prison overcrowding crisis following the Labor government’s emergency plan in 2024.

Tens of thousands of prisoners have already been released from prison under those measures.

Unlike the 2024 plan, the new act does not include parole for inmates convicted of serious crimes, domestic abuse or terrorism.

Prime Minister Andy Burnham said on Wednesday that he has promised to completely change the policy but will look at it in detail before moving forward.

He also admitted that there was “pressure on prisons” and that the lack of investment in the system had created an “unacceptable situation”.

Adlam said her message to Burnham was to “look at the big picture of the country.”

“As a country you can’t have a justice system that works like this. Just saying it’s full doesn’t mean it’s enough to release people. You have to find ways and I want to know what’s being thought.”

“I think the justice system has been lacking for some time and needs proper maintenance.”

Asked whether the plan would go ahead, chief secretary to the Treasury Emma Reynolds told the BBC: “That’s something he (Burnham) and the justice secretary will be putting out in the coming weeks.”

“When we take office in 2024, we have inherited a system … where there are less than 100 prisons, which I know is victim comfort, we have to take care of.”