i really love these. i bought like 30 of them ages ago but ive never actually thought of a use for them
it was definitely needed then as these radios were on VHF frequencies but used AM rather than FM and would pick up any random noise/interference as well as the intended signal, in the late 90s/early 00s (after the shift to VHF hi from Band II) we got away with many raves in rural areas of SE England near the Continent as in summer foreign TV soundtracks could end up on the Police radio control room channel, and the cops didn't want to take risks without reliable comms...
@jk they tended to get used for frequency/channel selectors on public service radio equipment, particularly Police radio schemes of the late 1970s to early 1990s.
I think Burndept went bust, most of these mainscheme sets got replaced by Cleartones with membrane/touch sensitive keys on the control head..