Thanks Acme.
Card-free games like that are quite interesting. There seems to be an assumption they're rare, but looking at the stats they happen every week (although CB would not be high up the list of likely candidates), and they seem to involve certain refs rather more often than the law of averages would suggest.
BTW, the advice to be wary of Soccerbase was good, it's been confirmed to me that there were only 5 cards in Argyle -v- Pompey on Monday.