RTFM --
I see that Kate Hoey, the local MP, is already starting to have a go at helicopters being able to fly around central London -- how about stopping developers from building ego-boosting tall buildings instead...
Idiots like that are just making noise for the publicity. If you restrict GA both fixed and rotary you'll degrade London as a hub for the sake of a bit of green-eye. This accident will have a cause, and it will be a series of events not just one 'failure' - 99% of accidents are. Unless this is a type issue (seems unlikely) then it isn't going to happen again other than by bizarre fluke (which sadly does happen) until the AAIB comes out.
Pure speculation on my part and no evidence related to this tragedy, I fear over-reliance on GPS particularly running on evolving platforms with evolving software. But I don't know it that's a factor here.