Chaps,
I write ths with a slight amount of caution. I'm sure that it applies to an old lifetime CAA PPL - I'm not sure about the JAA PPL. If you apply for a Medical Declaration from your GP and fly on that, without having to physically change it, your license is then equal to an NPPL/LAPL.
I'm not sure whether this applies to EASA reg. aircraft. You might be restricted to Permit/Annex 2.
Non commercial pilot licensing is at present a nightmare of bureaucracy. A mate of mine has just been through it and reports that not even the people charged with its administration properly understand what is going on.