One of the enduring benefits of emigrating at an early age is that you are not expected to attend school reunions; a benefit all the greater if the school you attended is in a city long synonymous with rain and grime, and now also famous for its gun crime. Why, then, have I flown halfway round the planet to attend a Manchester Grammar Old Boys dinner? Because if there’s one school reunion you should attend it’s probably the one that marks the school’s 500th birthday.