Young men could volunteer for the army at 17
for training / duty at home in uk but could not be
sent abroad to fight till 18 . There was conscription
at 18 when it was realized there was a shortage
of volunteers. However many big lads took themselves off to the recruiting office lied about their age / no birth certs. needed in those days. If
their parents found them in time they could demand
for them to be released , in some cases they were
already dead.[ or could not be found having used an
alias.] The navy always took in boy sailors straight
from school as at St George here in WW2.