Henceforth couples rotation will be enforced in the workshops, although those who have come to work specifically with their partner will be invited to mention it at the beginning so they can be left alone.
So if you were thinking about booking, now you know. Many thanks to Sophie for taking the trouble.
[Edit 1st Jan 09: it didn't happen, though, or at least not always. I took one of the all-levels couple classes, and there was no rotation, and no attempt to rotate. No one piped up and asked to rotate, either. Luckily for me, I'd booked with a suitable partner.]