A Family Mystery

So JC has history homework on the 1st World War and has to find if he has family connections through the war graves site. We can't find any links to our direct family when dad remembers some photos grandpa had left in his papers before he died. And here is the mystery. Why were they there? No knows the people and from the family tree we can't at the moment find any links through the name. The story behind the picture of John Lister is really sad. On the 1911 census it say he was 16 and still at school. This photo and war grave memorial show that he was dead four years later, killed on sentry duty. His parent were Mr & Mrs WH Lister of 22 Cecil Avenue, Bradford. The house is still there found it on google maps. The search continues.