In 1945, Seretse Khama, the heir to a chieftainship in Bechuanaland (now Botswana), came to Britain to study at Balliol. Whilst in England he fell in love and married Ruth Williams, a white woman. A gigantic, almost global weight of disapproval and hatred fell upon the young couple. They were exiled in Britain for six years before being allowed to return to Bechuanaland, where Seretse became one of Africa's great leaders and his wife an inspiration to the black women there, who loved and admired her.

This is an inspiring story, a disgusting one, and a reminder of two things: how ‘institutional racism’ plays out and lingers, and how dishonest are British governments, regardless of party. Susan Williams, of the Institute of Commonwealth Studies at the University of London, refreshingly sprinkles the text of her excellent and shaming book with ‘lie’ when no other word will do.

The cover photograph of the Khamas says a lot about character and period. Ruth, slim and fair, is wearing a dark, discreetly fashionable coat with a brooch, a sweater with pearls, nylons, and black heels. Seretse, dark brown with a Forties moustache, is in a tan raincoat, and wears a