Hi Scott,
I should state that Heathrow is the exception with Class A. Most, if not all the other major airports in the UK have Class D airspace. A good case could be made for establishing Class C airspace around Heathrow, but for reasons I won't go into, this looks unlikely.
Another issue here in the UK is that GA traffic generally is looked upon in some quarters as an irritation or a distraction. It doesn't generate any major revenue to ATS providers, but resources such as equipment and manpower must still be made available to provide GA with a service. This is but one consequence of the privatisation of ATC, and this attitude is likely to become more prevalent in years to come, unless the GA fraternity are made to pay realistic fees for the services they currently receive free of charge.