As the title says really. £4.98 for 8 batteries, 2 (so 16 batteries) for £5.00.
From Asda website:
Long lasting power guaranteed One size one colour Duracell Plus Quality power, guaranteed to last TRY NOW Duracell Ultra Power Our most powerful alkaline battery. Press Powercheck™ to see the power inside.
Hope this is of use to some of you. I did a search and couldn't find it listed already.