"…it'll just be Radio Caroline and various small-time pirates on AM. Even the venerable longwave transmitter for Radio 4 is getting shut down in a couple of months sadly."
Even with this shortsighted decision, the size of the UK is such that FM and digital services can provide adequate coverage. But that's not the case for large countries like the US, Canada, Australia, etc. VHF services major population centres with comparative ease but it's essentially impossible for it to do so for vast sparsely-populated areas. This is where LF, MF and HF are effective.
Years ago I recall traveling by car from Sydney to Adelaide (Australia) which is about 1000 miles and the shortest route is to travel diagonally across the country (the longer way would be to travel the coastline where the population is larger and take in cities such as Melbourne).
Traveling cross-country meant going across sparsely-populated areas where local broadcast services were either nonexistent or very patchy (low power—just enough to service a small community). Nevertheless, that proved no problem as the ABC's (the Oz version of the BBC) capital city AM transmitters located in Sydney, Melbourne and Adelaide provided coverage all the way. Even though Melbourne wasn't on route at points along the way its transmitter was stronger than the other two. (I'd note that was the daytime coverage from all three transmitters sans skip.)
It would be impossible to provide that coverage with only three VHF transmittes no matter their power. Frankly, it'd be crazy to switch off AM transmissions in a country like Australia even if one discounted their strategic advantage.
Even with this shortsighted decision, the size of the UK is such that FM and digital services can provide adequate coverage. But that's not the case for large countries like the US, Canada, Australia, etc. VHF services major population centres with comparative ease but it's essentially impossible for it to do so for vast sparsely-populated areas. This is where LF, MF and HF are effective.
Years ago I recall traveling by car from Sydney to Adelaide (Australia) which is about 1000 miles and the shortest route is to travel diagonally across the country (the longer way would be to travel the coastline where the population is larger and take in cities such as Melbourne).
Traveling cross-country meant going across sparsely-populated areas where local broadcast services were either nonexistent or very patchy (low power—just enough to service a small community). Nevertheless, that proved no problem as the ABC's (the Oz version of the BBC) capital city AM transmitters located in Sydney, Melbourne and Adelaide provided coverage all the way. Even though Melbourne wasn't on route at points along the way its transmitter was stronger than the other two. (I'd note that was the daytime coverage from all three transmitters sans skip.)
It would be impossible to provide that coverage with only three VHF transmittes no matter their power. Frankly, it'd be crazy to switch off AM transmissions in a country like Australia even if one discounted their strategic advantage.