Logically I cannot see that it makes any difference, if he holds an ICAO PPL licence, whether it is a Part-21 types or a Permit to fly aircraft. A UK PPL holder is given an exemption to fly a Microlite in the UK following a checkout from a Microlite instructor. Any issue, if one exists, will likely to be between an aircraft with a C of A and an aircraft with a C of A (Microlite). The source to find out is to contact directly the Department of Transport (General Aviation dept.). The CAA will need to ask them anyway but may takes weeks/months to respond.
The government to simplify things adopted the whole of EU (EASA) legislation into UK law with the aim to amend over time. The CAA/ Dept. of Transport is doing this but it will take time because of the complexity. The Dept. of Transport are in a better position to give an answer in the shortest time.
Last edited by Fl1ingfrog; 19th May 2021 at 17:01.