WHAT do a student in New York, a farmer near Mexico City, a family in London and a nurse in Bangkok have in common? Increasing trouble paying their grocery bill. Since 2000, the average price of food around the world has nearly doubled. In the UK, food prices are rising at three times the rate of inflation. In the US, the price of eggs has risen by 40 per cent in the past year alone, while rice in Thailand and tortillas in Mexico have shot up in price, in some places trebling. This year the soaring cost of food has triggered street demonstrations in 30 countries, some of which tipped over into riots.