Jan I have no desire to enter in to a fruitless debate with you, because if you seriously believe that pilots are quite entitled to clog up an
active ATS frequency with pilot to pilot calls, then nothing I can say is likely to change that.
And again: there exists no such thing as an "air/ground frequency". (or it should be another UK peculiarity).
And just so you know, in the UK there are numerous Air to Ground Radio frequencies allocated. Here is just one of those facilities, extracted from the White Waltham entry in the UK AIP.
A/G Watham Radio 122.600