I worked it for 18 years at Newcastle, when they only had a small class D zone, less towards the end when Newcastle was linked into the airways system. It is manageable especially now the military are significantly reduced. At times it can be difficult I remember giving a BA B752 three virtual orbits on its way to Pole hill trying to keep my 5nm from military fast jets. We used to have LHR controllers come up on FAM flights and say they couldn't do this!! Happy days....