If we are going to have a monarchy, and all signs point to that continuing to be the case for the foreseeable future, we should be clear about that. Justin Mortimer's hugely controversial beheaded queen of 1997 was interpreted as being disrespectful, but has a sinister mystery about it, a touch of regal distance and difference, unreality, sublimity, thrilling terror. It makes you yearn for a Francis Bacon study of the monarch (if only). Pietro Annigoni's 1955 portrait of the young Queen is often cited as the best made, and it is a superb combination of technical excellence, reliable likeness and moody windswept majesty. There's also a great deal to be said for the same artist's less popular 1969 portrait of Elizabeth robed in scarlet, a fearsome figure against an epic, blasted horizon. “I did not want to paint her as a film star,” says Annigoni in the explanatory note that accompanies this painting in the National Portrait Galley. “I saw her as a monarch, alone in the problems of her responsibility.” Damn right. What's needed from royal portraits is a bit of sublimity and awe – some of that “cosmic power” Strong saw crackling around the Tudor Elizabeth.