How green is your supermarket?

Supermarkets are taking steps to appear more eco-friendly, from charging for plastic bags to promoting sustainable foods. But does it make any difference to you, the shopper? And what does it cost?

All the major UK supermarkets from Tesco through to Marks & Spencer pride themselves on giving the impression that they are "green" or "eco-friendly". They highlight using recycled carrier bags, recycled plastic packaging or sustainable fishing and farming to help support their case.