As is the norm with many of Jackson Pollock’s paintings, the provenance tells a different story. So it is with Blue Poles, the stand out painting in the current exhibition devoted to American expressionism at the Royal Academy in London. Pollock was not in the habit of giving names to his drip technique paintings, so Blue Poles started out as Number 11 when it was conceived in 1952. Two years later, Pollock had a change of heart and it became Blue Poles. It was acquired by a museum in Australia in the early 1970’s, and there it has remained until it popped up in this show, perhaps the most important in the Academy since the turn of the century. It’s absolutely huge – five metres long – and is veined by every method of casting paint onto a canvas, a visual translation of a score inspired by, perhaps, Charlie Parker. This is one of those mercurial works that you simply don’t look at, but look into, and breathes the essence of Pollock. And if you like Blue Poles, you should after skip across the road to the Blue Posts hostelry for a sundowner.