This epic historical drama is staged in Greenside’s tiny Fern Studio, and loses none of its power. The set is sparse; a stool, a couple of bits of costume, and a blackboard with a list of dates ranging from 1945 to 1974. A passionate lecture on atomic bombs kicks off the action and continues throughout the play, intercut by unnamed soldiers whose reports are increasingly harrowing. The change is marked by stark lighting, and a salute.

Most of the play belongs to Bertie; a composite character based on the true stories of servicemen sent to Christmas Island in the 1950s. They were there to witness nuclear tests, and to clean up the aftermath. The army didn’t warn them of the dangers, and none of them were volunteers.

In the beginning, Bertie is nervous about the rumours he’s heard. In a deft piece of interaction, he recruits the audience; he asks about the food – it’s fish again – he arranges a cricket match, and he jokes that he’s serious when he says he’ll marry Jenny. The camaraderie cleverly lays out the risks and the stakes, and heightens the terror of the first detonation. ‘Now I am become Death, the destroyer of worlds.’

Then it becomes normal. He witnesses more tests, he shovels piles of dead birds into a fire, he stops wearing the meagre protections. They eat, sleep, swim, and work in the toxic fallout.

It’s his return to civilian life that brings back the fear. His health is severely impacted, his children suffer, and because he signed the Official Secrets Act, he can’t talk about it – not even with his doctor.

It’s here that the play lurches into an angry polemic. Through his own research Bertie discovers his DNA has been corrupted. Along with other veterans – the thousand sons – he takes legal action. It fails. To the rest of the world, he sounds like an obsessive conspiracy theorist. He writes the years on the floor; 1976 to 2018. The venue sightlines mean most of the audience can only see agitated movements; as they exit across the stage, they could read it, or not. It’s a lot like life.

Jamie Sefton, the writer and actor of this solo show, is confident and confiding; his script is accessible and deeply moving. It deserves to be seen.