Interesting. I wondered if anything would come of that meeting at the CAA almost three years ago.
I was the RAF Mildenhall SOG representative to a military flier's forum talking about what, if any, changes were required.
I was a wallflower for most of it, the discussion not really being in my lane as a visiting user of the airspace whilst stationed at Mildenhall, but I found it interesting nonetheless and did provide input when asked.
As I recall, initially there was much rejection of any change by the then current military operators. Over the course of the day, they slowly decided they did indeed wish to change a few things and the result was not radically different from what very little I've been able to glean from this thread with regards to naming conventions (ie - moving from RAS/RIS/FIS).
Indeed, I do recall FIS was to be changed precisely because it was different than the rest of Europe so as not to confuse.
I do also recall that the CAA intended to talk to civil operators in a separate forum, as well as air traffic controllers on their own forum. So whilst this may, at first glance, seem to be a surprise, it has been being worked on for at least three years.
I do not have access to the changes, but if it's available on a website somewhere, I'd be interested in reading it as I'm about to be posted back to Mildenhall in May.
Kind Regards