Nothing to do with HaveQuick.....that is UHF only.
It's probably that POS known as Mascot Mincom - and the awful RAF audio circuits rather than the transmitters and receivers.
Years (and years) ago, the RAF Flying Prevention Branch (aka Air Traffickers) defined a new ATC radio control system which was ever-so-whizzy and included rapid T/Rx switching etc. Quite a gucci system.
But then someone else decided on new headsets and microphones. Unfortunately the impedance of the new headsets didn't match the Mascot Mincom thingy - so, ever since then you hear phantom clunks on every RAF frequency as other transmitters are keyed through mutual inductance - and every transmission from an RAF ATCU sounds as though it's being made through cotton wool.....
...or a WAAF's knickers? RAF VHF comms are universally appalling when compared to any civil VHF comms.