"Shock revelation for a bloke who owns a mansion near a UK SH base- helicopters fly low level day AND night."
Very true, but equally, in peacetime, and in a democracy, it's common sense for the armed forces to minimise the nuisance it creates, and to reduce its impact upon its civilian neighbours. Scheduling the bulk of your night flying training for the shortest, hottest nights of the year may therefore be counter-productive, and trying to achieve more of it when it's dark at 7.00 PM (with a cut-off time of 1.00 am or midnight) and when people don't have to have their windows open might be seen as being a sensible step.
And if OC Puma OCF is reading this, I hope the b*gger takes heed! Otherwise I'll have to get Crumpington out in the grounds with an SA-13......