You buy a player for £7m and, four years later after he has matured into an England international, you sell him for £7.5m. And then, a little under a year later, you buy him back for £15m.

As a parable of the illogical nature of the transfer market, the story of Jermain Defoe’s journey from Tottenham to Portsmouth and back again can hardly be bettered. Spurs have faced derision for effectively paying Portsmouth to take a player on loan for 12 months, but they are far from the only club guilty of such fickleness.