A fascinating drama that investigates the infamous Croydon poisonings is set to be screened by the BBC.

The programme sees actor, writer, director and producer Julian Fellowes guide us through the unsolved murders of three members of a 1920s upper middle-class family.

Julian Fellowes Investigates examines the mysterious death of Edmund Duff, who lived in South Park Hill Road, and Violet and Vera Sidney who lived in neighbouring Birdhurst Rise.

The three all died within a year of each other from arsenic poisoning.

Grace Duff, who was Edmund's wife, Violet's daughter and Vera's sister, has long been regarded as the prime suspect although no one has ever been charged with the murders.

Producer Clare Alan said the intriguing nature of the cases known as either the Croydon Poisonings or the Birdhurst Murders made it perfect for the Julian Fellowes trilogy.

She said: "I loved the idea of a suburban murder mystery and the Croydon Poisonings is very intriguing and fascinating.

"The murders were well publicised at the time so we used a lot of old newspaper articles to help us research.

"When you look around Birdhurst Rise and South Park Hill Road a lot of the places have survived and are still there.

"We even filmed in some of the houses in the area."

Clare says she was able to hear about 1920s life in Croydon firsthand as her grandparents lived in the borough during that time.

"My grandmother lived in Croydon at the time of the murders so I was able to talk to her and she helped me a lot.

"We went back to the newspaper libraries and talked to people who were in Croydon at the time.

"I've always lived in south London and my grandmother and grandfather both lived there so this is a case I am particularly interested in.

"I've always found this case very fascinating."

Julian Fellowes Investigates the Case of Violet Sidney is due to be broadcast on BBC One on December 30 at 9.45pm.