Angels of Death

Senior ministers in Steed's department start dropping dead of natural causes. Steed's team investigate the deaths and the common factor appears to be a health farm.

I was 7 years old when this was broadcast and it's the only one I remembered anything about (which is the scene in the white maze). I guess that makes it the most memorable one in my mind but it's actually quite a good story too. And any tv show in which Joanna Lumley and Hammer movie legend Caroline Munro fight each other has got to be worth watching anyway.