When to keep schtum!
One of the many lectures we had during early days at RAFC Cranwell was from the RAF Paying Agents, who explained how our mighty 16/3d per day would be paid into our accounts.
If I recall correctly, there were 2 agents in those days. One was Cox & Kings and the other (I think) was Glyn Mills. The lecture was being given by some smarmy banker, who advised us that it would be 'easier' for all concerned if we opened accounts at Cox & Kings.
This went completely against the advice I'd had from my own bank - "Don't move your account as you'd just be a number with them, whereas we know you personally". I casually mentioned this to my fellow cadets and others agreed.
Anyway, in the afternoon we were studying Service Writing or something equally exciting, when in came one of the 'D' Sqn Flt Cdrs. A weasely looking engineering officer (I think?), with something of the Reinhard Heydrich about his manner - and expression.
"Did one of you advise people not to open a bank account with Cox & Kings?", he demanded to know. Well, fortunately the blank stare technique had become well-practised by then, thanks to 'crowing' - so I wisely kept schtum. In fact I wasn't being in the least bit dishonest as I hadn't actually said "Don't open an account with Cox & Kings", I'd said "I've been advised not to move my existing account".
This 'D' Sqn Reichsprotektor's eyes swept the room looking for signs of guilt; finding none, he turned on his heel and left the room.
When to keep quiet was rapidly becoming second nature!