Dead right I 4-2: the Sunair HF gave it away. Though I was surprised to see the "Sunair Electronics Co USA" on the set. My memory must be fading: I would have sworn all the ones I used were made by AWA - Amalgamated Wireless Australia?
They all seemed to work pretty well though.
I've never seen a Drover actually fly, but have a vague recollection there might have been one in a museum at Southend. Always wondered what they were like to fly,
What cockpit? and Which Aerodrome - make PPRUNE worth looking at IMHO.
Cheers!