Bringing it up to date
At 18, John was old enough to join the army, although many younger people volunteered and lied about their age. The youngest person known to have died fighting in the British army in World War I was 14.
Today, the UK is one of only twenty countries in the world, and the only one in Europe, to recruit 16-year-olds into its armed forces. They cannot be sent on “active service” until they turn 18. However, a 16 or 17-year-old who joins the forces, after their first six months, is obliged to stay in the forces until turning 22.
If you would like to see the age limit for the UK's armed forces raised to 18, you can sign a petition at https://you.38degrees.org.uk/petitions/stop-recruitment-of-16-year-olds-into-the-uk-armed-forces.
His sister Alice wrote that the headmaster, Geoffrey Fisher, treated him [John] with “ostracism and contempt”.