There is little added value as long as there is not a one to one relation between any defined spot in airspace and a corresponding service/frequency.
While I must admit being not very well acquainted with the UK situation, I understand from the www that several planes may be flying quite close to another, all in class G, each listening and perhaps even occasionally transmitting, but on different frequencies. So they may well be communicating for all they are worth, respecting every rule, yet be on a collision course without anybody warning them. If I've got that right, it means R/T has little worth, OCAS.