I left the UK back in 2003 with a UK ATPL and flying the B737.
Been flying the B737 and then B777 in Australia since then.
I recently contacted UK CAA to see what I had to do to transfer to an EASA ATPL - they replied:
- initial medical at Gatwick
- skills test/IR in B777 sim with TRE
- TRE will check level 6 english during sim check
- pay the fee