Coffman Starter has covered all the various radio fits, of which I saw many. Here's a little elaboration.
The decision as to what aircraft had what fit mainly depended on where they were operated. Those AEFs at a civil airport tended to have VHF and those at a military airfield, the UHF. However, the airframes were rotated, so you could be operating a mix. For example, I did quite a bit of AEF summer camp flying from Coltishall using both the old pre-select VHF and later, the 720 channel Marconi set. Radio failures were common in the former (sometimes because the cadet was bored and had starting fiddling with switches) and we just used to recover visually landing on the grass strip without talking to anyone.
The AEFs had no requirement to fly IMC - and in fact most of the pilots weren't instrument rated - so there was no requirement to fit a second radio. However, the pilot training schools at Middle Wallop, Roburgh and Swinderby did. The second radio regulation came into force in the mid to late 80s, as the radio was the only bit of nav kit the Chippy had! The Army always had a standby UHF, the Navy had a 360 channel VHF, but only one Swinderby aircraft had a second radio. WD331 was used for the Air Racing season and a Dittel 720 channel glider radio had been fitted so the pilot could fly to civil airfields and when the PTR1751 was fitted, the decision to fit the whole Swinderby fleet with the Dittel was made. The aircraft retained the UHF blade aerials, but had a different white VHF whip aerial fitted to the tail, behind the rudder. This was different to the standard fit aerial which was under the right wing.
The PTR1751 controller in the front cockpit was a large device which fitted between the pilots legs and necessitated removing the P11 compass and fitting an E2 'Airpath' type compass on the front coming. It was highly complex and even had the switching and ability to control a Have-Quick frequency agile Anti-Jam radio. (Not fitted!). The Dittel installation was less than ideal. It was under the panel by the pilot's right knee and had no internal lighting and was very hard to tune. Selecting a new frequency involved tuning with your forefinger and thumb while holding a torch in between your little finger and palm while flying with your left hand. It has a number of pre-selects, so before strapping in, you could load the frequencies you knew you may need.
My logbook shows that I flew WG480 (Now owned by Dora-9 and the second aircraft in his most recent pic) from Swinderby to Manston on 5 Jun 1992. Time, 1:30 - all of it IMC navigating on DF bearings. When I got to Manston, they insisted on giving me VHF frequencies because I was a Chipmunk and the Manston Chippies only had VHF, despite my protests and requests for UHF frequencies. I nearly put myself into a severe UP (unusual position) trying to tune the damned Dittel just as I was being directed onto the PAR. On the ground, I called ATC and explained. Their SATCO responded by calling me back and bollocking me for flying IMC when I wasn't allowed to!