A friend has come up with this query, but since the answer might be interesting for other people (if there is one!) I shall put it to anyone who may know the answer:
If you have a TM, say Spanish to English and you want to have the same terms the other way round (English to Spanish)?
The only way I can think of (maybe I'm being too complicated here) is to export it to a text file, use Text to Table in Windows, change the order of the columns, turn back to text and then import as a new TM.
Does anyone have any ideas at all?
Thanks very much.