When author Michael Morpurgo started chatting to an old man in a village pub, he soon realised something extraordinary was happening.

The conversation took place 32 years ago, when Michael and his wife moved to Devon. “He was a man of 80. He had served in the First World War aged 17,” says Michael.

“I told him I’d come across an old painting of the British cavalry charging up a hill towards the German position, with horses caught in barbed wire. His eyes filled with tears as he told me that he was there with horses, too.

“I stayed with him by that fire for two hours as he talked of the horse he’d loved and left behind, how it had been sold to French butchers for meat. It felt like he was unburdening himself. His wife said later that he’d never spoken of it before.”

The old man went on to show Michael a collection of things he’d kept from the trenches. “I thought ‘he’s handing this to me’. Next day, I rang the Imperial War Museum and asked how many horses went to war and how many came back. They said about a million had gone - and 62,000 came back.”

That was just horses from Britain. About eight million are thought to have served in the war in total.

Michael decided to write about “the universal suffering of war, seen through a horse’s eyes”.

The result was his best-selling children’s book War Horse, which inspired a multi award-winning National Theatre production – coming to Bradford on its first-ever UK tour – and an Oscar-nominated Stephen Spielberg movie.

War Horse is the haunting story of a farm boy, Albert, and his beloved horse, Joey, sold to the Army for use in the First World World War. The horse is captured by the Germans and used to pull ambulance carts then ends up in No Man’s Land.

The production features remarkable puppetry by South Africa’s Handspring Puppet Company, bringing life-size horses and other animals to life on stage.

Now in its fourth year in London’s West End, multi award-winning War Horse is also running in America, Canada and Australia and opens in Berlin next year.

Speaking at this week’s launch of the UK tour, Michael said the National Theatre production had “huge integrity” and told of a lesser-known experience of war.

“I was a war baby, I grew up in Earl’s Court playing on bombsites. But it wasn’t the bombed buildings or ration books that made me aware of what war had done – it was my mother’s eyes as she remembered the death of her brother, Pieter, who was shot down in 1941. You don’t forget grief, that’s what I learned.

“What I went on to learn was that almost as many horses as men died, and they died the same way – on the wire, in the mud, machine-gunned, from poisonous gas and exhaustion.”

Former Children’s Laureate Michael has written more than 100 books. Next weekend, as part of the Ilkley Literature Festival, he tells the moving story of a soldier’s letter found in an antique desk which revealed the Christmas Truce of 1914, marked by an Anglo-German football match in No Man’s Land. Michael will be accompanied by a cappella carols from singing ensemble Coope, Boys and Simpson.

Called The Best Christmas Present In The World, the event is at King’s Hall, Ilkley, on Saturday, October 13 at 2pm. Ring (01943) 816714.

Tonight, Michael talks about his work at Haworth’s West Lane Baptist Centre, from 7pm, as part of the Bronte Parsonage’s contemporary arts programme. Ring (01535) 640188.

  • War Horse runs at the Alhambra from May 26 to June 14, 2014. Ring (01274) 432000.