TR
If you have more than 500 hours on type on an ICAO CAA/JAA will give it to without having to do a full course. Your ICAO TR has to be current and you need to do just an LPC with a JAA TRE. Pitch up at Gatwick with your ICAO TR and proof of 500 hours on type and your LPC form and you get the TR the same day.
If you are applying for a JAA ATPL then the LPC also serves as your ATPL skills test.
I have personally done this FAA Multi Crew Type to JAA TR.
Of course if you dont have the 500 hours on type then its not available to you