Best supermarket: Marks & Spencer

Supermarkets claim they are furiously working away to be greener. On the most important issue – climate change – they make a variety of bold claims that often cannot be verified because they involve hidden, unaudited work on things like transportation. In truth, though, almost all have made progress on the environment. They have cut packaging and the distribution of free plastic bags, ended the sale of threatened fish such as North Sea cod and skate, and stock more sustainably produced toilet and kitchen roll. Some are particularly good on certain issues – see Sainsbury's support for less damaging palm oil or Waitrose's policy of buying British meat, for instance. But there are marked differences, even considering that commitment tends to be correlated to the affluence of their customers: the outperforming Co-op, for instance, is strong on the environment and Fairtrade. The greenest supermarket, however, based on its overall performance, is Marks & Spencer.

Since it set out 100 ethical commitments in its "Plan A" three years ago, M&S has been walking the walk on green issues. Last November, Consumer Focus rated it "A" for the environment in a survey which assessed the top nine grocers on areas including climate change, waste and recycling, and sustainable fishing and farming. Since then M&S has announced a further 80 commitments to be hit by 2015 – including slashing carbon emissions by 35 per cent and sending no operation or construction waste to landfill – to make it "the world's most sustainable major retailer".

Sainsbury's also scored an A in the National Consumer Council report and is runner-up here.

Martin Hickman is The Independent's consumer affairs correspondent