I've already mentioned this on the rotorheads forum, but given that none of this nonsense is actually going to stop anyone filing a bogus FP, loading their aircraft to the gunnels with high explosive and then launching same at one of several Government/State buildings (before anyone has the chance to say 'scramble'), what precisely is this restriction supposed to achieve?!
Why not have a programme whereby all pilots who are likely to fly in the Restricted Zone apply to the CAA by June next year for approval to do so. All the individual due dili and security checks can be conducted and once approved, a unique code is posted to the applicant's private address in a similar fashion to an interweb banking PIN.
On taking off, the pilot QSY's to a specific 'Olympic' frequency, when he/she will be asked for the 3rd and 7th letter (or whatever) of the unique identifier, is given a unique approval code (i.e. the CAA 'knows' this pre-vetted pilot is not a risk) which may be quoted and checked by other en-route ATCs and filed in his/her log book for subsequent ignoring.
This would provide a much higher level of security than the FP idea, but with a lot less hassle and a lot more spontaneity. The current proposal is simply preposterous: inpractical and inadequate.