As far as I knew Gatwick only did JAR Class 1 and 2 in compliance with JAR - FCL3
Didn't think there was any CAA specific additions... in fact things like EEG have been dropped from the Class 1 due to JAR. EASA will change things further again, the point of JAR and EASA being to unify national safety standards.
JAR Class 1 and 2 medicals | Medical | Safety Regulation