I hope this is the most logical of the multiple threads to post this. 
Taking on board
Raffles's advice to think about matching
after the 8th of the month and to check the validity of existing status, I thought I'd check when our DC status expires.
Mrs Roger's card expires 09/12 and mine 08/12. OK, so our years expire six weeks or so before, right? Wrong!
Both Mrs Roger's and my membership years go to 16/07/12.

For Mrs Roger, that's 2 1/2 months before card expiry! So presumably we should both match on 9 July, and I will suggest that Mrs Roger does that.
As it happens, I would requalify for BA in August with planned revenue flights. Just the August outbound needed. One half of me says not to bother with the match yet - I'd just lose some status miles on the outbound in August - the other says to strike while the iron's hot. On reflection, perhaps wait until we know when the match offer will expire.