David Cameron has paid tribute to the fallen soldiers of the First World War, including his great-great-uncle, Captain Francis Mount.
Captain Mount - a relative on his mother's side of the family - was 43 years old when he volunteered to fight in the conflict.
ITV News Diplomatic Correspondent John Ray reports from Loos, northern France:
In 1915 Captain Mount was posted to Loos, northern France, where he fought as part of the Royal Berkshire Regiment.
But it was there that he died - killed in action during the Battle of Loos on 12 October, 1915.
The Prime Minister said of his ancestor, "Almost half of the people that he served with didn't come home, and it does help to make a personal connection with this massive sacrifice that took place."
One book tells how Captain Mount met his demise during the conflict:
Captain Mount's body was never found, and he became one of the many thousands of First World War soldiers who have no known grave.