G-baks & g-bcwm
KS and WM were both aircraft operated by Dollar at Coventry. I remember KS as the heaviest 206 as it had floats (at the time) and also a Janitrol heater. Only one I ever flew with one - fuel burn changed from 26US gp/h to 29.5.
Looking on G-INFo, I note that WM was owned in it's early days by the now Sir Norman Foster, a very smooth pilot who I had the pleasure of flying with on a few occasions.
NJT - I think you are mistaken with G-BCEU - it is a Cameron hot air balloon according to G-INFO