In response to ShyTorque, it may have escaped your notice that the whole question of operating helicopters over London is under close scrutiny and, more worryingly, great is the interest of the environmental lobby and politicians anxious to collect votes. It will only take a few more instances of Chinooks at 500 feet all the way down H4 and H3 to raise awareness of the noise problem. I, for one, would like to safeguard my livelihood for a little while longer.
No, it hasn't escaped my notice one little bit, thanks. However, sorry to say that I have absolutely no desire to be an airborne traffic policeman for yourself, the BHAB, or anyone else in order to "trap" military pilots.
As far as I'm concerned, our military crews are putting their lives on a daily basis in the middle east and I'm not. If they make a little more noise to train up for it then let them 'fill their boots'. Now you mention it; why shouldn't the public be reminded of it once in a while?