I never found any words to back this up but I guess it sounds reasonable.
CAP 1441 backs it up, for an EASA licence you do need an EASA medical certificate though you could still do a rating prof check without it you just couldn't exercise the privileges. For a national PPL (pre JAR) its different and CAP1441 makes it quite clear what medical is acceptable for its use. From the CAA Website:
Flying EASA Aircraft
There is an EU exemption that allows UK national licence holders to fly certain EASA aircraft until April 2018 that is limited to sailplanes, balloons and visual flight rules (VFR) flight in single engine piston aircraft no greater than 2000 kg MTOM with a maximum of 3 passengers.