Our National Treasures are instantly identifiable but difficult of definition. They are mostly rather old, but there's more to it: Stephen Fry and Joanna Lumley have been NTs for years, while David Beckham was finally ushered in at the Royal Wedding.
There, too, was the youngest of them all: Prince Harry. The absence of his brother from the treasury shows the advantage of a little roguery.
But too much edge won't do: Michael McIntyre's almost there; Ricky Gervais never will be. Overriding all seems to be the detection, rightly or wrongly, of an innate, dread word, niceness.
Can you imagine David Attenborough jumping the queue? Judi Dench nicking your parking space? Sir Cliff breaking wind? How about, though: Maggie Smith telling you to f-off? David Starkey not wanting to hurt your feelings? Sir Keith Richards listening intently to the route you took? Difficult. Perhaps we could get Professor Stephen Hawking, Sir Bobby Charlton and Dame Shirley Bassey to discuss it.