Well, I'm afraid that those contributors haven't yet caught up with the changes in legislation! 'Group A' disappeared years ago!
If the aeroplane weighs more than 450 kg, it cannot be a microlight. Hence if it isn't a self-launching motor glider or touring motor glider, if it's powered by a single piston engine then it must by default be a SEP aeroplane. The BMAA should be able to assist you with any specific query; however, if the aircraft is G-M***, then it's a Microlight!
Perhaps it'd be easier if you asked "Can I keep my PPL(A) SEP Class Rating valid by hours flown in a ????" But don't forget the training flight requirement!