foreign registered aircraft are only allowed to flyin UK airspace for 30 days per yr.
Are they? There is no limit.
But any EASA aircraft registered in an EU member state can fly in any other member state without restriction.
So can any non EASA registered aircraft.
Apologies for being pedantic
but currently there are no long term "foreign reg" parking limits anywhere in the EU, that I know of. I heard Denmark has such a rule but nobody I know knows how (or if) they enforce it.
But yes the French always get what they want, EASA or no EASA.
The UK CAA is very money motivated; they need to make their 6% return and that is their main driver.