What are witches knickers?

So, what are witches knickers and what do they have to do with Tesco?

Well, witches' knickers is what the Irish call plastic bags fluttering in trees. You can see why, especially at night. Tescos are going to try and reward shoppers by giving them extra club points if they reuse any bags or bring their own.  In Germany you pay for any bags. That's a much better incentive IMHO.

Photo from Tim Parkinson.