Can you either -
Apply to the CAA for a UK National PPL (ICAO complaint licence), which should be OK with a PMD? They don't seem to have a form for it, website says in a couple of places: "If you wish to apply for a UK national PPL, you must submit your request in writing by email to
[email protected] (with the subject heading: 'National licence')."
This is not an NPPL and avoids the downgrade.
Or - persuade an AME to issue a Class 2 if possible, with safety pilot restriction? Even if the Class 2 said safety pilot, it's still a Class 2 and gets you into the Part FCL issue process?
You don't need any solo flight to renew your class rating and once you've done so, you rely on the PMD.