'Truth or Dare' murder of Heysham grandmother to feature in Channel 5 documentary

Truth or Dare: The Murder of Mary Gregory features the story of how a game of Truth or Dare led to her tragic murder.

Student Tiernan Darnton, 21, trapped his stepfather’s mother 94-year-old Mary Gregory in a blaze at her home in Heysham in 2018.

Her death was treated as an accident until Darnton, who had confessed to the killing in a game of truth or dare, made a similar confession during counselling in 2019.

In November 2021, he was sentenced to life with a minimum term of 15 years.

Darnton claimed he had disabled a fire alarm and started the fire because he did not want Mrs Gregory to suffer any longer from dementia.

The court heard at the time that "disturbing material," which was not presented to the jury during the trial, had also been found in Darnton's possession, including plans to stalk and attack women and a "kill list" with people's names on.

The jury at the time was told an initial investigation had concluded that Mrs Gregory, who was a heavy smoker, had died in an accidental fire on 28 May 2018.

However, police reopened the case in May 2019 after Darnton told a counsellor he had killed his stepfather's mother by using a lighter to set a curtain on fire at the house in Levens Drive.

The court heard he had also confessed several weeks after Mrs Gregory's death, during a game of truth or dare with two friends in which he revealed his "darkest secret".

But he later claimed he only wanted to impress his "edgy" friends in the truth or dare game and was "attention-seeking" with the counsellor, who he claimed had fabricated parts of their conversation.

Mrs Gregory's son Peter said in court that he never accepted that Mrs Gregory died in an accident.

Lancashire police detectives will be discussing the case in the programme.

Truth or Dare: The Murder of Mary Gregory will be shown on Channel 5 at 10pm on Wednesday, (October 25).