scotsflyingboy: having worked at tesco in the past I can guarantee you would soon be wishing you could spend you last 5 working years at BA instead.
most people at 55 who retire these days are quickly bored and enjoy being back at work. given that people are going to live till they are 80 on average very few people want to spend 25 years doing nothing
remember - you quickly become senile when you're bored and stop using your brain.