After their feature-length documentary Spitfire, David Fairhead and Ant Palmer return with a wartime history of the Lancaster bomber. With its encyclopedic detail and commanding narration by Charles Dance, this feels like a film for second world war buffs and aviation enthusiasts. Everyone else will stay for the interviews with the now elderly men who flew bombers as lads (teenagers some of them) at terrifying odds: 55,573 airmen out of 125,000 were killed during the war. Returning from missions, they measured lost mates by empty seats in the dining room.

The film is expertly bolted together from archive newsreels, snippets of classic war movies and interviews with surviving airmen from Britain and one from Jamaica: Neil Flanigan. The Lancaster first saw service in 1942, as the RAF shifted tactics from targeting German factories to entire cities. There’s extraordinary footage here of test runs in Kent of the bouncing bombs dropped on German dams in the Ruhr valley, immortalised in The Dam Busters.

Still, this is not a jingoistic or triumphant film. A German woman who witnessed the destruction of Dresden as a child is interviewed. “The dead lying around in heaps,” she remembers. “Mountains of dead people who burned to death.” Some of the veterans talk about their horror at what they inflicted on civilians below. “War’s a dirty business, isn’t it,” says one. Another says he couldn’t talk about his experiences after the war. “People looked at you like you were a murderer.” For another, evidence of the Nazis’ crimes in the concentration camps made it easier for him to justify what he’d been ordered to do. It feels deeply unfair that after so much was asked of these men so young, guilt haunted them for the rest of their lives.

• Lancaster is released on 27 May in cinemas.