The BBC’s celebration of the Queen’s ninetieth birthday was wonderfully site-appropriate. While BBC1 – among much else – offered Nicholas Witchell’s matey encounter with Prince William, the World Service weighed in with Sir David Cannadine’s sober analysis of Her Majesty’s role as an international stateswoman (20 April).

Not that “sober” is quite the mot juste, as Sir David, unlike certain historians, has both an engaging manner and a sense of humour – the latter no doubt tickled pink by someone’s description of the Commonwealth as “the after-care service of the British Empire”.