Yesterday was 'the calm after a storm' (and a particularly bad storm at that - 68ft waves reported off Cornwall). The day started off with a heavy frost, but then the sun came out, and after an hour or two so did the bees. Every hive put a cloud of bees into the air - which is always a good sight to see after weeks of confinement.
I mention this as a comparison - for I've never yet had a colony abscond in the way being described, nor have I ever heard of this happening to anyone else in Britain. It is true that from time to time reporters trying to make-up an alarmist story will claim CCD-type absconding has been observed in parts of Europe, but losing colonies by swarming or by winter starvation (both of which do happen, sure) is not the same thing at all. I'd suggest that it's a softer option for incompetent or lazy beekeepers to jump on 'the CCD bandwagon', than face up to their own mistakes.
For those in Southern areas relying on swarms for their stocks, I'd suggest buying a queen from 'up North' - say, from someone like Michael Palmer who has never seen absconding or CCD - and breed your working queens from her. It's not a perfect solution, of course, as you've still got your local drones to contend with - but at least by starting-off with a stable maternal line you may be able to retain sufficient European genetics to at least get your colonies to stay put (assuming of course that it's Africanisation that's responsible). If you then go on to buy one new queen from 'up North' every two years or so (which isn't a major expense, compared with the expense of lost colonies) from which to breed, you could at least then cope whilst a more permanent solution is found.
LJ