Roger Mosey is the Master of Selwyn College, Cambridge, and was formerly editorial director and the director of London 2012 at the BBC. The idea of having to buy a licence to watch television may seem like a relic. But the principle behind the funding of the BBC is simple: if we all pay for something then we have a stake in an organisation which is designed to serve the public. And in a time when our society is fracturing, and media moving from the universal to the personal, there is still a common good in preserving a space where the British people can talk to each other.