The defence of the realm is the primary duty of any prime minister and, so far as this particular legacy is concerned, David Cameron may be tempted to congratulate himself on a job well done as he exits Downing Street.

During six years of premiership, Mr Cameron has scaled back Britain’s military involvement in overseas conflicts to the point where we no longer witness the bodies of soldiers being paraded through the streets, as was often the case in the Wiltshire town of Royal Wootton Bassett when the Afghan campaign was at its height.