With Walkers displaying carbon labels on its crisps and Tesco slapping airplane stickers on produce flown in by jet, consumers are being forced to think about the impact of their food choices on the planet. This is not premature. The skyrocketing price of oil, combined with competition from biofuel production and demand from the booming middle classes of China and India, who want to eat like Britons and Americans, have stressed the global food chain to breaking point.

But the current food crisis is nothing new, according to Carolyn Steel in her wide-ranging and engaging book, Hungry City: How Food Shapes Our Lives . Cities have struggled to feed themselves since man first got sick of chasing woolly mammoths around with sticks and set about domesticating grain instead - around 10,000 BC. Food transport has always been the limiting factor on the growth of a metropolis; indeed "food miles" used to be a measure of a city's power. Those with access to the sea or rivers had a huge advantage over the landlocked. Athens could import grain from the Black Sea and imperial Rome turned northern Africa into its bread basket. Later, London's location on the Thames gave it an edge over Paris, which, despite the Seine, was too far from the sea for large-scale importing of grain.