Sir: Tesco's generosity over bananas ("Banana economics", 15 January) is not the only occasion on which it has made sacrifices for customers. Three years ago Tesco issued vouchers to students at Bristol University entitling them to 50p off sandwiches. This coincided with a half-price sandwich offer. For a week we were able to purchase egg-and-cress sandwiches at a price of approximately 5p. For us there was such a thing as a free lunch.