Guardian: On the outskirts of Heathrow there is a multistorey warehouse that plays a remarkable role in the eating habits of millions of people. The British Airways perishables handling centre is the arrival point for 90,000 tonnes of airfreighted fresh produce a year: everything from chopped melon and pineapple fruit salads to baby sweetcorn and asparagus. Every day these once exotic items arrive in the belly of passenger jets from Africa and Asia, destined for the chilled aisles of supermarkets such …