Mark Gatiss praised after tearful 'Stand Up to Cancer' video about losing his mother and sister to the disease

Sherlock co-creator Mark Gatiss delivered a tearful message to viewers of Celebrity SAS: Who Dares Wins on Sunday when he discussed losing his mother and sister to cancer.

Viewers took to social media to praise the 52-year-old actor and writer for the honesty and sincerity of his video message for Stand Up to Cancer.

Read more: Sherlock voted top TV theme tune

The heartfelt video aired during one of the advertising breaks of the survival programme, in which well-known faces including presenter Jeff Brazier, Love Island star Camilla Thurlow and former Olympian Victoria Pendleton were put through their paces.

In the charity appeal, Gatiss shared the story of losing his mother to cancer and subsequently having to deal with the fact his sister died as a result of the illness soon after.

“It’s an extraordinary thing to say, but one of my happiest family memories was the week that my mother was dying,” said Gatiss.

“My sister and my brother and my cousin and I, lots of people we sat around the bed and just laughed and told stories about her, and to her, and just remembered stuff.”

Read more: Russell Brand wins Celebrity Bake Off for Stand Up to Cancer

He later discussed making preparations to spend Christmas with his sister, only to be told that she would not live until that day following her own breast cancer diagnosis.

Gatiss said: “It just seems so completely unfair that it was happening again so soon, but that’s the truth of it.”

Viewers were impressed by the candour of Gatiss’ message and took to Twitter to praise him for having the courage to share his experiences.

Gatiss co-created Sherlock with former Doctor Who showrunner Steven Moffat and also starred in the show as Mycroft Holmes.

He was previously best known as a member of the comedy troupe The League of Gentlemen and has since played a representative of the Iron Bank in Game of Thrones.