When you are young, the yellowed, curled pages of your grandfather’s diaries are perhaps not of much interest. But when he looked through them a few years ago, he thought, “This is astonishing.”

Stewart’s grandfather was a captain with a Scottish regiment in the First World War, and he kept a record of his daily experiences stationed in the Somme and Passchendaele. Many entries that might seem mundane in other circumstances, such as the chance to have a bath, take on a fresh import. Other stories, such as the reaction of Flemish citizens when your troop descends on their town, or when the mud reaches your armpits, or when you suddenly feel a rat licking at the grease in your hair, bring the day-to-day life of an officer on the frontline into wary focus.

Captain Alexander Stewart was the only officer of his intake to survive the war, and, once home, he elaborated on the diaries, creating a memoir.The diaries remained a family heirloom for 70 years and Cameron finally decided to publish them in e-book form in 2007. The following year, he recorded it as a talking book and read some excerpts on the Today programme on BBC Radio 4. “And then all hell broke loose, really,” he says.

The public response was enormous. The memoirs brought the war into living rooms and kitchens, and provided some British people with their first real understanding of the horrors of the frontline and the devastating loss of life. The prose is sensitive, informative, anecdotal. Britain fell in love with it.

Cameron’s grandfather had titled his memoir The Experiences of a Very Unimportant Officer in France and Flanders during 1916 – 1917, and a hardcover was published in 2008 by Hodder & Stoughton under the title A Very Unimportant Officer.

So Cameron had done what his mother, now deceased, had told him he should do. But he is, after all, an actor. He premiered the one-man show My Grandfather’s Great War at the Edinburgh Festival in 2008, and the Daily Telegraph called it “the most affecting show in town”. He’s now toured it across Britain, and, fittingly, Flanders will be the first stop on his international tour.

The English Theatre of Bruges, which keeps a sharp eye on the best of Edinburgh, will host the show in its tiny, 30-seat theatre. Cameron has performed it for both small and larger audiences, but in such an intimate setting, he says, “I feel like I’m actually talking to them. Which gives it a different slant.”

The show re-enacts some of his grandfather’s experiences verbatim from the diaries, mixed with his own reflections on the concept of war. “I’m rather torn because I have an awful lot of respect for soldiers and especially for my grandfather… but I abhor war,” he says. “I was a bit worried that soldiers wouldn’t like it, but quite a few of them have come to see it, and they’ve really enjoyed it and liked what I’m saying.”

My Grandfather’s Great War

22-24 January, 20.00

English Theatre of Bruges, Walplein 23

www.ematema.com