The widow of slain Pc Andrew Harper has written to unions seeking their support for her campaign to create a new law meaning those who kill emergency workers are jailed for life.

Lissie Harper has contacted the Fire Brigades Union, the Prison Officers Association, Unison, Unite, the Royal College of Nursing, the British Medical Association and the General Medical Council in an attempt to harvest the backing of hundreds of thousands of emergency service workers.

Mrs Harper said it was her “strong belief that society must offer the greatest protection for those killed protecting it”, adding that she did not believe current laws reflected that.

In her open letter, Mrs Harper said: “For too long have criminals been able to commit crime, cause harm and take the lives of the innocent.

“This needs to change and I need your support in order to do that.”

Pc Harper, 28, had been married for four weeks when he and a Thames Valley Police colleague responded to a late-night burglary in Sulhamstead, Berkshire, in August last year.

Two of Pc Harper’s killers, 18-year-olds Albert Bowers and Jessie Cole, last week lodged applications with the Court of Appeal seeking permission to challenge their convictions and their 13-year jail sentences.

Let’s show the criminals and killers of this world that they cannot cause our heroes to fall without paying the price, we will not let this stand any longer

They were jailed alongside Henry Long, 19, who was handed a 16-year sentence.

All three were acquitted of murder during a trial at the Old Bailey but were sentenced for the lesser charge of manslaughter after Pc Harper got caught in a crane strap attached to the back of a car driven by Long, and was dragged to his death along dark country lanes.

Those sentences have also been referred to the Court of Appeal by Attorney General Suella Braverman for judges to decide whether they were too lenient.

More than 450,000 people have signed a petition backing Harper’s Law, which would see anyone convicted of killing an emergency services worker given a life sentence.

In her letter on Monday, Mrs Harper said: “To take a life should mean a life sentence in prison.

“That is what Harper’s Law will provide – an appropriate deterrent and a suitable punishment.

“Far too often our heroes are taken for granted, attacked and assaulted.

“And on rare occasion their lives are cruelly taken.

“My husband was one of these heroes, one of the protectors who gave everything to his job as a police officer.

“He was an impressive police officer and never did anything by halves.

“Yet it is now, after his life has been taken that he has been let down, let down by the very laws that he fought to implement every day that he proudly wore his uniform.

“He deserved so very much more than that.

“I want to change the way that our country views our emergency services workers.

“I want our Government to offer them the most protection they can.

“Ultimately, I want to provide justice for those who will deserve it most of all.”

She added: “To take the life of an emergency services worker should mean facing a life sentence in prison.

“Let’s give our protectors the ultimate protection.

“Let’s show the criminals and killers of this world that they cannot cause our heroes to fall without paying the price, we will not let this stand any longer.”

She urged emergency services workers to “keep spreading the word” about Harper’s Law, and asked them to contact politicians and to share the petition to achieve the legal change.

Mrs Harper added: “I hope that together we will achieve Harper’s Law.”