Happy families are all alike but each unhappy family, so we have been taught, is unhappy in its own way. The sprawling clan to which Harriet Spencer, Countess of Bessborough, belonged found entirely new ways of ensuring its unhappiness. To begin with, generations of intermarrying meant that only a handful of people in the eighteenth-century aristocracy were not Harriet’s cousins, making it virtually impossible for her ever to leave home; secondly, she had the misfortune to be born to parents who adored one another, which instantly made her an orphan. Nonetheless, Harriet and her elder sister, Georgiana, Duchess of Devonshire, were adored by everyone else (except their husbands), and the two of them had London society sewn up: you were sleeping with either one or the other.

Georgiana lived in a ménage à trois with her husband, the Duke, and her best friend, Bess. Accompanied by the latter, the Duchess would periodically cross the Channel to welcome another little bastard to the world