MICHAEL Morpurgo may be best known for writing War Horse but his fascination with the untold stories of the First World War also led to him writing Private Peaceful.

The former children’s laureate is now hoping the story of 18-year-old Private Tommo Peaceful will prove as popular on the stage as his biggest theatre success.

The stage play of War Horse has been seen by seven million people, and many more have seen the Steven Spielberg film based on the book.

The origins of Private Peaceful go back 20 years, to Morpurgo visiting First World War exhibits in a museum at Ypres in Belgium. As he was leaving, a framed letter caught his eye, its envelope addressed to a woman in Manchester.

“This typed letter was so stark,” Morpurgo remembers. “It said: ‘We regret to inform you that your son was shot at dawn on such-and-such a date. Yours sincerely’. I looked at the envelope and there was a huge tear along it.

“What that tear told me was the moment that this woman’s life had fallen apart. She opened it, and the rest of her life was grief and shame.”

He then discovered that around 300 British men had been executed during the First World War for various acts, including desertion, cowardice, even two who had been shot for falling asleep at their post.

Files at the museum contained details of the trials. “One of them lasted less than 20 minutes,” says Morpurgo. “The vast majority were suffering from post-traumatic stress disorder, or shell shock as it was called.

“I walked out thinking this was a part of history people did not know enough about. This was not justice.”

Moved by the letter, Morpurgo started writing a story about two brothers, Tommo and Charlie, who are wrenched from their rural life to fight in the war, with the story of the executions playing a major part.

The story became Private Peaceful, an award-winning book for older children published in 2003. The story made it to the stage thanks to writer and director Simon Reade, who was running Bristol Old Vic Theatre. The show opened in 2004 and toured the world for 15 years.

In 2019, Reade decided to expand the play with a bigger cast, with the original ending reinstated. Everything was set for a premiere in 2020 and then the pandemic caused all the theatres to shut.

The new version of Private Peaceful is touring the UK tour and coming to the Yvonne Arnaud Theatre at Guildford. Morpurgo is delighted because the story is a way of dealing with difficult themes unflinchingly.

“My first profession was as a teacher,” he says. “I got used to explaining the world in a way that interested children but was not traumatic. You can tell them things at the right moment in the right way. It’s also important that they have to know.

“Children grow up so much more savvy now than I did. They know there are difficult things in the world. They can see the world at its cruellest, broadcast directly to them. What you do not do is avoid talking about these things.”

Private Peaceful will be at the Yvonne Arnaud Theatre, Guildford, from 23-25 May.