One-third of young people in the UK think ham comes from chickens and oranges grow in Britain.

These were the results of a MORI survey of eight to 11-year-olds for the National Farmers Union in 2004.

Knowing where your food comes from might not seem important when all we want is laid out so cheaply on shop shelves but the luxury of yearround goods and supermarkets comes at a much bigger price.

Defra estimated that in 2004, transporting food accounted for 38 per cent of all HGV journeys, causing carbon dioxide emissions of 18 million tonnes - enough to fill every house in Brighton 180 times.

About 95 per cent of fruit and 50 per cent of our vegetables are imported - so is it really possible to survive on a completely local diet?

Kat Neeser, 34, is an organiser of monthly eco talk shop Greenspeak and, in her daily life, an administrator for a large company. She lives in Hove with two friends, does not shop in supermarkets and where ever possible eats locally and with the seasons.

She says: "The absolute basis of eating locally and seasonally is to not buy something from abroad if it is being grown in the UK. Supermarkets often import foods even when they are in season here."

According to Brighton and Hove Food Partnership, which is working to develop a local food network for the city, it is often cheaper to import food than buy it locally because of international trade rules.

In fact, in 2002, we imported 16.1 million tonnes of food which is native to the UK.

So what actually defines local?

The Lanes-based food shop Sussex and the City sources everything from within a 50-mile radius and boasts plenty of food, drinks and even a selection of 25 cheeses.

Kat says about half her diet is made up of locally-sourced vegetables: "I count the UK as local if I can't get any closer. The main thing is that it's in season and hasn't flown anywhere.

The bread I buy is made in Sussex but the grain is not from here so it gets a bit confusing. You just have to be informed and make your own choice."

Another way to go local is to grow your own. John Fryer is part of the Whitehawk Community Food Project, a patch of several allotments worked by groups of volunteers.

"As far as veg, fruit and herbs go, I am completely self-sufficient," he says. "I experimented with grains suited to small-scale production but you need such a huge area of land for just one person it's not viable."

Kat also finds issues with locallysourced grains. "Vegetables are fine but grain is a problem. If you ate spelt a wheat grain from medieval times now enjoying a revival as a health food all the time you could probably do it all UK local - but generally it's very hard to get hold of," she says.

"With veg I just go to Infinity Foods and buy whatever is labelled UK and local. You have to be creative, though.

At the moment I don't make salads with lettuce, I use finely-chopped white cabbage."

Then there is the issue of tinned and dried goods. Your tinned plum tomatoes or dried pasta are not going to be from Sussex - or even the UK.

Kate Wood from veggie box delivery company Real Food Direct says: "It has to fit in with your life and be practical. Are you really never going to eat a banana again?

"I don't think there is anywhere in the UK which actually produces tinned goods. Eating ten per cent local food forever is better than trying to do 100 per cent for a week and then giving up. If you go completely overboard it's like a New Year's resolution you can't possibly keep."

  • Help out at Whitehawk Community Food Project, open Thursdays and Sundays from 12 till dusk at Whitehawk Hill allotments. Call John 07900 126817 or visit www.thefoodproject.org.uk
  • Discover how dwindling oil stocks could force the global food system to go local at Greenspeak, April 17, 7pm. Free. Terraces Bar and Grill, Madeira Terrace. Call Kat on 07958 964810 for more details.

Do you buy locally or grow your own food? We'd like to hear about your experiences. Please leave your comments below.