This Newsnight article with Justin King (Sainsbury's CEO) addresses the issue of plastic bags and packaging and points out that the issue has many facets.

However, I feel that we are getting the message wrong. People feel good these days if they recycle (destroy and remanufacture), whereas the emphasis should be on reusing; there is nothing wrong with the punnets that our meat, fruit and veg come in. If the supermarkets standardised on the trays they used, they could collect and reuse them in much the same way as Lemonade and milk bottles of old were. Unfortunately, I suspect that Health and Safety tsars would stop this...