Worth bagging one for next winter IMO.
These were flagged up on HUKD when they were reduced to £9.99 a couple of months back but have since been further reduced to clear.
I found my one displayed in a central promotional section along with a rather random selection of other offers. My local Sainsburys only had Kingsize but it's possible that other stores may have doubles, or singles similarly reduced if they've got any left.
I don't know if their careline can pull up info on which stores hold stock but if they can, the order number off the packaging is 064/011 and the careline number is 0800 636262.