The latest instalment of BBC’s Crime Next Door strand investigates the brutal deaths of brother and sister Griff and Patti Thomas on an isolated Welsh farm in 1976. It’s a series that’s already got fine form; earlier this year, Kaye Adams examined the astonishing 1988 attempted assassination of Croatian dissident Nikola Štedul, gunned down in a quiet Kirkcaldy street by a Yugoslav secret-police agent.

Death On The Farm is a more intimate tragedy, focusing on the campaign to clear Griff’s name; a frail elderly man who, according to the police report at the time, supposedly smashed up furniture in the farmhouse he shared with his sister, bludgeoned her to death, inexplicably sustained a head injury himself from a sewing machine (and then somehow placed the cover back on it), before setting a fire in which he laid down to die. As you listen to each of the six episodes, it seems increasingly unbelievable that investigators didn’t consider it plausible that this could be a double homicide, not a murder suicide.

In one of the podcast’s most devastating moments, the minister at the chapel (which these devoted siblings attended all their lives) turns his back on them, refusing to let their coffins enter his church. Guided by the gentle narration of Bettrys Jones, what emerges is the tale of a community and family seeking justice, refusing to let Griff and Patti be forgotten almost half a century on.

Crime Next Door: Death On The Far is available now.