Widger,
If you want to have a credible RAF then they have to have somewhere to train that is not affected by civilian aircraft trying to save a few pounds/seconds. By terminating a 4v4 exercise to avoid triggering a civvy TCAS costs several tonnes of fuel - imagine asking AN Other airline to burn 8 tonnes of fuel to hold while the RAF finish their training. The airways exist for a reason and while all users should use Class G airspace in a sensible manner, once again it is the military that suck the hind tit in these scenarios. More TCAS and airprox warnings might make the general public aware of how theses airlines like to 'mix it up' with the military.
SG