I'm in the odd position of enjoying flying around london but also finding helicopter noise a bit tedious at certain times.
My ear's good enough now to pick out the royal london hems even when i don't see it and that seems (and this is partly about perception) fairly quiet. The noisy ones (from an east london point of view) are the police doing the circling routine and it's the circling (perhaps because of low level?) that you get a bit bored of.
Maybe Ken can get all the bad people to behave (they live north of me) then it'll be quieter
