Throws up some interesting links to producers. Not only London as the name and details suggest but also around the country. It is easy to use and seems to list some that you may not know.

The Local Food Finder

http://www.sustainweb.org/ethicaleats/localfoodfinder/

Drawing on our extensive directory of local suppliers, we suggest practical ways sustainable ingredients - such as local and seasonal fruit and vegetables, high-welfare meat, sustainable fish, organic and Fairtrade produce - can be incorporated into menus.
Do get in touch with us if you have any questions on buying sustainably or click here for more information.
We also promote ethical eating to consumers, to encourage them to choose sustainable options when eating out.
Ethical eaters have long been offered a cornucopia of sustainable food in London’s shops and markets - but until recently, when they ate out, they had to leave their principles at the restaurant door. In recent years, a growing number of restaurants and catering businesses have started to use more local, seasonal, organic and Fairtrade produce. And with Britons now spending more on out-of-home meals than on grocery shopping, and some research showing we’re eating more out-of-home meals than any other country including the US, the potential market for sustainable dining is huge.
London-based restaurants, cafés, pubs and caterers doing great things are selected by the Ethical Eats team to be highlighted in The Jellied Eel magazine’s On the Menu section. Events such as our popular Restaurant Rambles aim to raise the profile of ethical food providers and get consumers thinking about dining out decisions.
For more information on consumer attitudes to sustainable dining download the London Food Link report One Planet Dining.