The caretaker at my primary school (Mr W) served in the Coldstream Guards during WWII.
I remember him telling Dad about his guard duties at
Chequers.
Churchill was in the habit of walking alone in the wooded grounds in the dead of night as it gave him the opportunity to think without interruption.
On one occasion the PM suddenly appeared, said 'Good evening, sentry' and equally suddenly disappeared once more into the darkness before a salute and a spluttered 'Good evening, sir!' was returned.
Mr W admitted to being somewhat frightened at the time!
Good job he didn't shoot him.