A petition to block the early release of PC Andrew Harper’s killers has been signed by more than one million people.

The police officer, from Wallingford, Oxfordshire, died in 2019 when he was dragged by a car as three teenagers fled the scene of a quad bike theft in Berkshire.

Jessie Cole and Albert Bowers were sentenced to 13 years for his manslaughter in 2020 but could be released next year under plans to tackle prison overcrowding. The prime minister is looking at ways to keep them in jail.

Thames Valley Police (TVP) Federation acknowledged the important milestone the petition had reached “without fanfare” due to the seventh anniversary of the officer’s death on Saturday.

The petition was started by TVP federation chair Aileen O’Connor who said the decision to consider the killers for early release “pours salt into wounds that have never healed”.

She added it was an “insult to Andrew’s family, his friends, his colleagues and the entire policing family”.

The federation thanked all those who have signed in support.

Under changes to the Sentencing Act made this year, Cole and Bowers will become eligible for release in January after serving half of their sentences.

They are in a category of prisoners who until now would have had to serve at least two-thirds of their terms before being considered for release.

A third man jailed for manslaughter – the vehicle driver Henry Long – was given a longer 16-year jail term and cannot be considered for the new early release conditions.

Pressure has been mounting on PM Andy Burnham to change their eligibility with two open letters sent to him – one from 50 police chiefs and another from 13 Thames Valley politicians from all three parties.

Both said those who kill an emergency worker while committing a crime should be excluded from an early release scheme aimed at easing prison overcrowding.

Burnham has already asked his justice secretary to fast-track a plan for presentation to Parliament early next month to create more “headroom” in the prison system.

But he added it was “simply not possible to prevent all offenders from being released early without the prison system collapsing”.