I've investigated further and it appears that there are different euro spec tpms depending on the year of the car. My friend in good faith quoted me the part number for his euro spec 1999 car, but mine is a 2001 and needs part number 20807214 (from the one I took off). Looking on the net is quite confusing as some info I've found about part number 10354987 is that it is for a euro car, but others say it's for a US frequency - confusing or what. Upshot is I'll get one from rockauto, and when I change it out I'll have the wrong one up for grabs. Incidentally, both items looked identical, and the one I bought had made in UK written on it's packaging, so one would assume it was euro spec.
Pete