> And if the native crops are simply not as good nutritionally as the new crop then it's better to eat the new crop even at the ecological cost of the native one, e.g. potatoes vs barley in Ireland.

Potatoes and barley both grow pretty well in the UK.

The problem with eating things like soya over here is that you can only do it if you burn a city's worth of diesel every single day to power a container ship to bring it, and it's farmed using horribly unsustainable methods.

The stuff I eat (he says, drinking a cup of Colombian coffee, okay okay, hypocrisy) is grown using techniques and ecological impact more-or-less unchanged from the dawn of agriculture. We use Massey-Fergusons now rather than horses or oxen but there would be nothing stopping you going back to horses, and indeed with diesel at nearly two quid a litre it might well be worth looking at that.