Update. Reported via Fixmystreet. Sainsbury's have been in touch (very promptly). Feedback via Fixmystreet:

“Sainsbury have replied.The Rentokil pest contactors have confirmed the main reason for the rats is the residents putting down food and water for the birds. We don’t have any pest activity within the store or the surrounding car park, but the problem has been raised at the base of the car park by the bus stop. Traps have been laid, but all the time the rats have a food source made readily available by the residents, they will stay away from the traps State changed to: Internal referral”

If you live round the Bell Green retain site, including Sainsbury's, or you go there from time to time, please please please don't leave food out, even if you intend it for the birds - it just feeds the rats. They won't even waste time going to investigate the delicious poison in the bait stations if people are leaving plenty of food for the birds.

thanks,

BigED