Hi nickso and JohnD,
Thank you for your replies. I neglected to mention that I am currently renting the house so don't have immediate access to photograph the rad valves. However, I will be going to the house this weekend, so will get some pictures for anyone interested in seeing early...
I have radiators in my house which have really old Drayton thermostatic valves - does anyone know if it is still possible to obtain parts for these?
I have some operating instructions for the radiator valves which identify the valve type as Drayton 73-03 (stated as "previously S.215 & S.233")...