Indications are that it's going to be an on-line system but not sure of the cost.
Is this legal under European law?
As described by Billiebob, the system would indeed be illegal under European Law. It would violate at least three articles of the Treaty:
Article 26 (2) :
The internal market shall comprise an area without internal frontiers in which the free movement of goods, persons, services and capital is ensured in accordance with the provisions of the Treaties.
Article 34 :
Quantitative restrictions on imports and all measures having equivalent effect shall be prohibited between Member States.
relating mainly to the internal market and
Article 107 (2) :
Save as otherwise provided in the Treaties, any aid granted by a Member State or through State resources in any form whatsoever which distorts or threatens to distort competition by favouring certain undertakings or the production of certain goods shall, in so far as it affects trade between
Member States, be incompatible with the internal market.
which relates to competition law (Making foreign examiners pay when local examiners do not have to pay for a briefing is an illegal subsidy of UK examiners).
If you are a foreign examiner wishing to accomodate UK applicants (students at a UK CAA registered facility or training organisation) you should ask the UK CAA in writing
(a) What the precise cost would be
(b) What justifies this cost
(c) Whether the same cost applies to UK CAA designated examiners
Based on the answer, it is a violation of either internal market law or competition law
You can then make an official complaint to the relevant directorate at the European Commission and ask for a meeting with the relevant officials to see what their appetite is to take the UK CAA to court (which is by far the cheapest option);
or take the UK CAA directly to Court in Luxembourg. If you win your case convincingly, you also get awarded your legal costs (count on investing roughly £5,000-£10,000, depending on how much legal spadework you do yourself).
Because any EU citizen can take the UK CAA to court, and because the UK CAA cannot afford 20-odd law suits on this topic, I believe that
(a) the fee the CAA will charge will
not be a recurrent fee, as it becomes much easier to demonstrate that it is an artificial trade barrier rather than a true briefing cost.
(b) the actual fee, when implemented, will likely be
less than the current £630, because is will be more difficult to justify that it corresponds to the true cost of a briefing, especially if it is a mere online application, and that the costs are incurred
in surplus of what they normally have to spend on briefing the existing UK CAA examiners.