Just to correct several comments (including it appears official ones) that the aircraft has moved "across the river", it has not entered the River Thames at all. It has been barged across the Royal Albert Dock, which is the one to the north of the LCY runway. It is opposite approximately the midpoint of the runway.
Originally Posted by safetypee
I do not know of any special installations or tricks associated with the 146/RJ at LCY.
I think you will find the 146 comes down the whole final approach with its rear fuselage airbrakes deployed. This is different to any other approach I have seen them do elsewhere where they are usually deployed just as coming over the threshhold.