'Out of season' isn't really code, and there's differing degrees of local. You can get a lot of decent food sourced from within 50 miles of where I live, even more if you expand this to the whole of Britain, more for the EU still, more for the world. Much of the really out-of-season stuff we get here is from New Zealand or Argentina - many of the foodstuffs from Africa and the Caribbean aren't exactly available for growing in these colder climes...

Apart from fuel costs (in all senses), you've also got the problem of taste. Strawberries picked halfway across the world and freighted over here, ripening in containers are never going to taste remotely as good as those picked just up the road yesterday.

The easy way to judge, though, is on price and special offer. Our local supermarkets stock local produce a lot of the time, and it's easy to tell when something is in season: it's marked as half-price or BOGOF. This isn't a loss-leader, it's not a special deal with a farming group (their margins are already pared to the bone as it is), it's just that they're easy to get hold of cheaply.

Cheaper, fresher, more sustainable... What more do you want?

(The debate now goes to the impact on countries in the developing world who have made a good living selling food to the West...)