HE PENNED his first poem as a seven-year-old pupil at Oxford’s The Dragon School.

In the decades since, Jon Stallworthy has won many awards for his poetry, books and editing skills.

Now Professor Emeritus of English at Oxford University, his portrait of First World War poet Wilfred Owen was described by author Graham Greene as “surely one of the finest biographies of our time”.

Next month, The New Oxford Book of War Poetry, which the 79-year-old edited, will mark the centenary of the outbreak of the First World War.

His interest in war was sparked during his early days at The Dragon in the 1940s, against the backdrop of the Second World War.

A number of his teachers had been injured during the conflict, including one with a steel plate in his head, and there was a school plaque commemorating the dead.

It was The Oxford Book of Modern Verse 1892–1935, a collection of poems edited by Irish poet WB Yeats, that led him to write about Wilfred Owen. A long introduction by Yeats includes an explanation why he left out the war poets, such as Wilfred Owen.

Prof Stallworthy said: “I was interested in why Yeats so disliked and disapproved of Owen.

“I realised it was all about ancient versus modern and how the world had changed.”

While working as an editor at Oxford University Press in the early 1970s, he was introduced to Owen’s brother Harold, who asked if he would write a biography and edit the poems.

There was limited material for the biography, since Owen was just 25 when he died, but OUP gave him a year off to write it.

The biography proved a fairly straightforward task but editing the poems took 10 years. Owen wrote most of them during 1917-18, before being killed in action in November 1918, and although he saw five in print, he left a mass of unpublished work.

Prof Stallworthy said: “There were three or four hundred pieces of paper with fragments of poems but we couldn’t date anything, so it was hard to know which he had intended to be his final versions.”

It suddenly struck him that Owen had dated all letters he wrote to family and friends.

“Although he was a poor boy, I noticed the paper on which he wrote his poems was very good quality and was the same as he used when he letter-wrote.”

By matching the paper, pencil, ink and 24 watermarks of the undated manuscripts with those of the poet’s letters, he slowly but surely solved the riddle.

The final result was the publication of the double-volume Wilfred Owen: The Complete Poems and Fragments.