I was a 'D'-Man once. I think I was the youngest for a while, most of 'em were 'rather older'. Eventually the sectors became too busy for procedural control with radar 'intervention' and the 'radar' tail started wagging the 'procedural' dog, hence 'Mediator'. It was quite a challenge when the radar was out and we had to revert to the old 'T1 + T2' formulae' (can anyone remind me of them?) In 'Stage Half' the 'A'-Side was (wo)manned by ATCA IIs but there was always at least one ATCO III on each bank to make executive decisions on behalf of the D-Men. In 'Stage One Mediator' each Sector had an ATCO III ASC in addition to an ATCA II SA. The ATCA did the strip-bashing and the ATCO III did the cruising level allocation and the coord. If one had a good ATCA who was maybe cadet material one could leave them to it on a 'long lead' and have a bit of fun. I have a nice collection of photographs of the North Side in action fifty years ago. The other job of the ATCO III was to do the FIR hence the anachronism 'FIR Controller'. It meant they could get a good grounding on using the wireless. Heady days....fond memories.