There are 2 types of own brand Alkaline in Tesco right now,
Extra Long Life @ £2.50 4pk
and Long Life @ £1.50 4pk
Tesco Long Life Alkaline AA
500mA 1468mAh
1A 1020mAh
Tesco Extra Long Life Alkaline AA
500mA 1525mAh + 6.79272%
1A 1086mAh + 6.47059%
Tesco Long Life Alkaline AAA
200mA 822mAh
500mA 537mAh
Tesco Extra Long Life Alkaline AAA
200mA 821mAh - 0.121655%
500mA 574mAh + 6.89013%
So spend 66.6% more and you only get an extra 6.5% ish life (with the exception of the AAA Extra at 200mA, might test that again)
All my results on my funny looking site, all batteries bought in the UK.