OhNoCB
Nobody knows, not even Balpa yet
From Balpa newsletter :
Pilot Licences. This is covered in Article AIRTRN.18: Aviation Safety, paragraph 2, where mutual recognition with a minimum standard of the ICAO Chicago Convention is established. Prior to the agreement being struck, the CAA were suggesting that UK licence holders flying EU registered aircraft after the 1st of Jan would need to acquire an EASA, EU based licence or obtain an EASA validation of their UK licence. However, this article seems to supersede that requirement, albeit coming much too late for anyone to take advantage of it. BALPA will seek to confirm beyond doubt, as a matter of priority, if there is now full, mutual recognition agreed for UK and EU issued pilots licences and ratings, etc., without further cost or cumbersome bureaucracy.