LONDON.- As it launches a major exhibition of actress portraits, the National Portrait Gallery has announced the acquisition of a large and rarely seen picture of three of eighteenth-century society’s most glamorous and notorious women – as the three witches from Shakespeare’s Macbeth. Georgiana, Duchess of Devonshire and Elizabeth Lamb, Viscountess Melbourne – the most famous political hostesses and society beauties of their day – are shown gathered around the witches’ cauldron alongside their friend, the sculptor Anne Seymour Damer. The portrait will be seen by museum visitors for the first time at the National Portrait Gallery’s autumn exhibition The First Actresses: Nell Gwyn to Sarah Siddons, where it will be included in a section devoted to amateur dramatics. It was acquired through the Government’s