Bex... Several Heathrow ATCOs validated on the TMA but no TMA people came to Heathrow while I was at TC.
"My father is a RAF Controller" Don't worry, GavReal - he'll probably get over it!! Worst thing I ever saw in my life was in the Approach Room at Luqa, Malta. A senior NCO (in rank and age) who was much respected by his colleagues was given a major dressing down in front of everyone because one of his shoes was dirty from having been on the airfield. The dressing down came from some little spotty-faced squirt of a Pilot Officer who looked about 16. It's things like that that put me right off the RAF so DON'T ever think of joining up.