Tesco are doing 2 x 6 pack for £6
The packs in Carlisle store are doing by 2 get 1 free by redeeming code at http://www.appletiserrewards.co.uk,
for which they will give you a voucher for £4.29.
Use this to buy two more for only £1.71 (£6 less £4.29)
If you register the next two at a different address you can get each additional 12 cans for £1.71
Seems a good deal :)