"Purple Airspace" is long gone. The LTMA is Class A, whether there's a "Royal" in it or not.
I suspect that this is a potential Level Bust by one or other of the parties involved. Level Busts are very much in the spotlight and everyone (Pilots and Controllers) are encouraged to report them, in order that 1) the statistical data is more accurate and 2) the causes can be evaluated and communicated to the entire aviation community in the interests of Flight Safety.
I use the word "potential" as 3nm and 900ft are within the tollerances used by LTCC, as explained by vectorline. Perhaps a high rate of closure set off someones TCAS?
Rgds BEX