Saw these in my local ASDA (Livingston, Scotland - EH54) just as I walked out main entrance. They had literally stacks of them so I can't imagine this being limited to this store. They're in a proper box rather than the usual" value bag".
I paid over £7 for a 6 pack in Morrison's just last week. This is the best supermarket deal I've ever seen on these. Wish I'd grabbed a pic now as I walked out the door. No idea if this deal is online.