bookworm,
Could you point me at the last mid-air collision in the UK that occurred in cloud please?
Must there be a mid-air collision in the UK in IMC in order to form the basis for establishing Class E airspace?
There must be reasons in Germany, France, USA, etc. for doing so. Presumably there have been mid-air collisions as well.
This is about adopting international best procedures and practices. It is not limited to mandating radio in IMC, but a number of other things such as defiining which sector provides services in an organized manner outside the terminal area, instead of a mash up of dis-jointed services.
Or do you just sit and wait until there is a mid-air in IMC and then look at the problem again?