For the sake of our cultural life, politicians like Bradshaw and Johnson should leave political drama to the artsArt and politics have always been, and always will be, locked in a complicated and often uncomfortable dance, from Velázquez's double-edged depiction of Pope Innocent X to Mark Wallinger's Turner prize-winning State Britain – a meticulous recreation of Brian Haw's Parliament Square peace camp.But politics and art have now become entangled in a manner at best unedifying, at worst damaging, to cultural life.It started last month when a newspaper ran a leaked letter from Liz Forgan, the chair of Arts Council England, to Ben Bradshaw, the secretary of state for culture, media and sport. (Full disclosure: Forgan also chairs the Scott Trust, ...