The issue in the UK for UAVs in restricted air space is the Detect and Avoid requirement. Essentially, if you want to fly via remote control, you need to demonstrate that your aircraft can detect other airspace users and take avoiding action. Currently there is not a certified system in existence, so flying beyond LOS is all but impossible to get permission to do.
One option with the DHL drug deliveries is to fly from 1 hospital helipad to another, with a pilot at each end to carry out the landings and to fly below 400' on autonomous flight in between. Quite tricky in a city as built up as London!
I think once there is a usable detect and avoid system - basically a 360 degree observation system, a radar transponder and certified failsafe system, this might become a reality. At the moment, it is seriously limited and for publicity purposes only.