Saturday night’s Culture Show on BBC4 told a remarkable story. Dr Bendor Grosvenor has rediscovered Allan Ramsay’s 1745 life portrait of Prince Charles Edward Stuart. You can’t exaggerate how important a find like this is, or what a triumph it is for an art historian. Thanks to Bendor, Ramsay’s oeuvre has acquired an extraordinarily beautiful painting and we get to see Bonnie Prince Charlie at the happiest moment of his life, when he was planning to sweep down to London and put his father on the throne. It is a symmetrical discovery, because Bendor’s previous coup was to prove that the Scottish National Portrait Gallery’s so-called portrait of  Bonnie Prince Charlie, a 1747 pastel by Maurice Quentin de la Tour was in fact a portrait of the Prince’s brother Henry Benedict. It was a much-loved portrait and the loss was keenly felt, proof of the great power these icons still have. Giving the Scots a new, far more compelling likeness by their greatest portraitist was a beautiful way of making amends. As Bendor shows in the programme, the portrait was designed as part of the Prince’s propaganda campaign, which included offering the Scots independence in return for their support. I am sure it will be re-enlisted in the cause.