I saw this sign in a 'very English' bookshop in the out of town shopping centre on Monday morning.  It made me smile.

I vaguely recall my mother telling us to 'haud yer wheesht' when we were children which equated roughly to 'be quiet and calm down'.

There are now any number of variants of this old war time poster, some more amusing than others.

Anyway, for a bit of completeness, here's the Welsh version...

(For some reason I saved this as a draft and forgot about it until now!)