I'm not sure which Sainsbury's this refers to, but I was in the Pet Shop part the Bell Green retail park with Sainsburys, PC world etc.

A group of around 8 schoolboys \ young men walked in and one was asked to leave as the rule was 'no schoolboys' without a parent present. It was a strange one, the boys were big but the kid who got asked to leave was heading to a section of the shop where I can't believe anything would be stolen (aquariums \ lizards section). I remember when I was young I would like to look at the animals in the pet shop.

Shoplifting is of course a huge problem for shops, and of course you cannot tell a shoplifter from looking at them. I personally think a limit of x amount of kids at a time as you often see in newsagents might be best, a compromise of sorts.

As with many things, there is no easy answer, but I suspect the answer here lies through the schools and parenting as mentioned above.