The token thingy on my key ring is exactly the same size as the £1 coin. Comparing the 1 euro coin with the £1 coin, they both look identical in diameter but, as said, the £1 is (noticeably) thicker. You'll have to try the thingy when you get there! Guess is it won't work because the euro trolley abroad is set too narrow to take the thicker coin/ thingy; it may be that ours work with both sometimes because the diameter is of both coins is so close the thinner euro fits .
(Psst - pd, if you are going to forge coins you might want to do a bit of research before you start, if this is your research, you might want to think of another career)
And isn't that a damn nuisance in airports? Nice is/was a good'un. You need a euro coin for the baggage trolley, the foreign exchange hasn't given you any, the cash machines only give notes, and the change machine to change notes to coins is out of service. Have a good trip!