Will Stone’s film about the Scottish mass shooting shows how the parents fought through the pain to have the UK’s gun laws changed in the face of political cowardice and the hostility of the pro-gun lobby

Teacher Gwen Mayor, who was killed in the Dunblane massacre in 1996, with her class of children, 16 of whom also died. Photo: Mathieu Polak/Getty Images
Thirty years ago next month, a man armed with two 9mm Browning semi-automatic pistols and two .357 Magnum revolvers parked his car at the primary school in the Scottish town of Dunblane.
He entered the gymnasium and opened fire, murdering 16 children, aged between five and six and in their first year of school, and a teacher, Gwen Mayor, before killing himself.