As the queues formed down the street outside branches of Northern Rock this week, it was obvious enough to a game theorist what was going on: people had decided to hunt rabbits. Bear with me – this will make sense in a moment.

Game theory is the study (by economists, mathematicians, biologists and others) of situations where what you do may affect what I choose to do, and what I do may affect what you choose to do. The theory is big on catchy stories with memorable names, but ultimately it is all about mathematical representations of interactive decisions, called “games”. The most famous game of all is the “prisoners’ dilemma”, in which two prisoners must each decide whether to plea-bargain by giving evidence against the other.