The posthumous pardons awarded as recently as 2006 to shell-shocked soldiers executed for desertion and other battlefield offences during the First World War have given a new topicality to John Wilson’s fine play on the subject. First seen in 1964 as Hamp – when it set John Hurt, who played the deserter of that name, on the road to stardom – the work was filmed later that year by Joseph Losey as King and Country, with Tom Courtenay cast as the innocent victim of the Army’s intransigence and Dirk Bogarde as the young officer charged with trying to save him from the firing squad. Now this gripping – and to a large degree shaming – story is being told for a new generation as the renamed For King and Country embarks on a national tour.

I was pleased to see many young people in the first night audience at the Everyman Theatre , Cheltenham, on Tuesday. Even as the last handful of the Great War’s survivors succumb to the grave, the ghastly conflict clearly still maintains its power on the imagination. Directed by Tristram Powell, with a first-rate cast and evocative sets and costumes by Tim Shortall, the play offers 90 minutes of deeply moving action (played without interval) leading to an inevitable but nonetheless shocking end that no one surely can witness without a tear in the eye.

The focus of our sympathies is Private Arthur Hamp (the excellent Adam Gillen), a 23-year-old volunteer from Co. Durham who by the time the story is set, during the Third Battle of Ypres, has seen nearly three years of service and almost all of his colleagues fall one by one. The horror of a fellow Lambtonian being blown to smithereens beside him, his own near drowning in a mud-filled shell crater and a Dear John letter from his faithless wife combine to send him on the run. Though clearly ill, he has been treated merely as a malingerer by an unsympathetic army doctor (Patrick Drury) who clearly recognises (what was presumably true) that any leeway in matters such as these would result in a stampede of men eager to leave the line.

In the opinion of his court martial prosecutor (Martin Savage) “he has let fear become his master rather than mastering it as was required”. This view is confirmed by the panel of judges, led by its rules-are-rules president (David Yelland).

That Hamp is blind to his fate, and too innocently honest to speak words that would secure his safety, is a source of agony to his impassioned defender, Lieut William Hargreaves, superbly presented in his upright decency by Daniel Weyman, who was hugely impressive last year in the title role of Nicholas Nickleby in the West End. At one point, when Hamp is asked if he planned to return to the line, he needs only to say that he had. Sadly for him, in this moment of high drama, he is unable to dissemble.

The play ends, brutally, with Hamp insensible on rum and morphine carried away to the firing squad after a botched attempt by the kindly padre (Kevin Doyle) to give him communion (see above). The offstage execution is botched, too, and a coup de grace has to be administered by an officer. The task falls not, as in the film, to Lieut Hargreaves but to Hamp’s platoon commander (Dugald Bruce-Lockhart), another basically decent man whose outlook has been altered for ever by exposure to the horrors of life and death in the trenches.

For King and Country continues until Saturday at the Everyman (tel. 01242 572573 www.everymantheatre.org.uk).