20 MHz was also approximately the point where aerial noise had declined to the point where receiver front end noise became dominant in terms of defining overall performance. Some HF receiver makers, both in the commercial and consumer domains, used “VHF” valves in the RF amplifier/1st RF amplifier position in order to obtain good noise factors in the 20-to-30 MHz range. Most common I think was the use of high-slope, sharp cutoff VHF pentodes, such as the 6AK5, Z77, 6F1, etc. Occasionally high-slope, remote cutoff VHF pentodes such as the EF85 were used, and late in the valve era the cascode RF amplifier (e.g. ECC189) was found. Another approach was the use of a grounded-grid triode (or triode-strapped pentode) with aperiodic input as an RF pre-stage.
Conversely, some tunable VHF and VHF-UHF communications receivers tuned below 30 MHz, usually to somewhere in the 20 to 30 MHz range, for example 25 MHz in the case of the ICOM R7000. That I think is an indication of the pseudo-VHF nature of that frequency region.
The technology required for TV tuners probably helped push the envelope both in the VHF and UHF cases. In the early 1950s, VHF TV tuners went to 216 MHz or so at a time when few VHF communications receivers went that high. Eddystone had planned 210 MHz for the 770M, but couldn’t get it to work properly so settled for 165 MHz with the 770R. The range above that was left to the 770U, using UHF techniques, and that went only to 500 MHz, whereas UHF TV tuners of the time went to around 900 MHz. For the 500 to 1000 MHz range, Eddystone offered the highly specialized 770S, which was originally described as an EHF receiver, although it was being described as UHF by the early 1960s.
Returning to the original question, a reasonable deduction is that RMorg uses “UHF” according to its apparent pre-Atlantic City 1947 meaning, which referred to anything above 30 MHz. That meaning may have been established by customary usage in that period rather than by formal definition.
RMorg also uses another old convention, namely tuned circuit count. Apparently, that was a sales feature in Germany in the immediate post-WWII period, as noted in this Wireless World 1950 November item. Note that the FM band was still being referred as the EHF band. (It looks as the WW editorial staff were being a bit stubborn about adopting the Atlantic City designations.)
Tuned circuit count was not unknown in the UK, though. Dynatron’s late 1940s/early 1950s tuner-control unit combinations, such as the T69, T99 and T57, were designated according to valve count and tuned circuit count. So, the T69 had six valves and nine tuned circuits. The count evidently included the oscillator tuned circuit.
Cheers,