‘Happiness, happiness, the greatest gift that I possess,’ trilled comedian Ken Dodd in a pop song from a more innocent age. There’s been a lot of guff written about happiness in recent times. On the one hand, you’ve got the positive thinking gurus peddling their often simplistic fast track to deep joy and on the other you’ve got the doom-mongers telling us we’re richer, healthier and unhappier than we’ve ever been.