i've got it to do what i need, probably not in the most effective way but i've managed.

The problem with what i was trying was (i think) that the method was comparing the list as a whole, whereas i needed to compare each name and subject combination. Well i have now set up a sheet that takes the both names and subject into 1 column, then compares these for the old and new data. This has given me the required result.

Incidentally, i've used COUNTIF()=0 and COUNTIF()=1. Am I right in thinking that with "=0" it returns entries that are not shared between lists, while with "=1" it will return entries that are on both lists?

This seems to work with the example of data i've used, will test it on the real thing in work tomorrow.

Fingers crossed!!