As ever - great answers from PPRuNers(I've read alot more than just this post) - so Skydriller, AA & Vedeneyev thanks for your info.
At least I understand what happening a bit more and the NATO link suggests there will be little flying at weekends.
I'll aim to keep clear of the low fly zones - if only I had the option to get in the way at 20,000'
Cheers
D&O