IO,
The privileges which some license gives the pilot of a G-reg are specified in the UK ANO. The ANO (Article 26, IIRC) limits the usefulness of an ICAO (non-JAA) IR to IFR outside controlled airspace i.e. IFR in Class G or F only. This is not very useful; you could fly IFR to Norwich (Class G) but not Bournemouth (Class D). And much of Europe is at least Class E.
This is interesting : you're saying effectively that another European country could authorise the use of an FAA/PPL/IR in all CAS in aeroplanes of their own national reg ?
Is this actually the case anywhere ?
FF