Sir Trevor McDonald’s blood ran cold as he drove down the dark Berkshire lane where a brave police officer was dragged to death by a speeding car.

The veteran newscaster was filming a heartbreaking documentary about PC Andrew Harper’s young widow Lissie’s campaign for a change in the law to prevent other families from going through what she had.

Sir Trevor appears visibly shocked as he visits the location where PC Harper jumped out of a police car to confront three thieves who were towing a stolen quadbike behind a car.

As they drove away, the 28-year-old officer’s legs became entangled in the tow rope attached to the back of the Seat, and he was dragged along the road.

“I can’t tell you how shocked I was,” Sir Trevor says in an exclusive interview with The Sun.

“The overwhelming feeling is one of profound sadness and tragedy about how he died.”

“I couldn’t believe he was finished with his shift.” He had finished his work for the day and was on his way home when he answered a 999 call and was dragged down that dark road.

“His coworkers noticed his stab vest before they noticed his mangled body.” It’s just too tragic to put into words.”

Since her husband’s brutal murder, Lissie has fought to ensure that anyone who kills an emergency worker is sentenced to life in prison.

Surprisingly, Harper’s Law will be enacted into British law in less than three years.

“I want to create some kind of legacy, something that I know Andrew would be proud of.

“Otherwise, it’s a just a disgraceful waste of an amazing person’s life.”