16 blades
I think you have a dedicated area called the HRA, open every PM from 1500-2300 Mon-Thu. Given the size of HM's aviation department you could probably all go at once and not bump into each other!
The UK has a great deal of dedicated Restricted areas, Danger areas, Notam'd areas all active on a daily basis making commercial operations a pain in the butt. I would like to say that the military are cooperative in the use of this airspace when it is known to be empty but I have found that not to be the case, in fact completely opposite and the standard of military controllers is often less than good.