Living next to LCY, and watching the departures daily, I can tell you that the RJ85 is by no means the noisiest aircraft out of the airport. In fact it is one of the quietest. There is another prevalent type which is far more prominent, and in fact is noticeably different in its operation between its different operators - one in particular seems to gun the throttle more than others.
I wonder also how any local authority can just change the conditions under which an aircraft operator has run for many years, and at two months notice. Surely this is CAA territory.