In 1873, as Leonard Jerome argued with the Duke of Marlborough about the size of the financial settlement he was prepared to hand over to his future son-in-law, Lord Randolph Churchill, Jerome told his daughter Jennie that, in spite of the haggling, he was thrilled by her imminent marriage. It was ‘the greatest match any American has made since the Dutchess (sic) of Leeds’, he told her, referring to Louisa Hervey-Bathurst (née Caton) of Baltimore, who in 1828 married Francis Godolphin D’Arcy Osborne, Marquess of Carmarthen and in line to succeed his father as 7th Duke of Leeds.

The story of how Louisa, a 33-year-old childless widow, came to marry ‘Car’ (as he was called), who was five years younger than her, is arguably the high point of this enthralling book. Not only was Lord Carmarthen tall, handsome, fair-haired and engaging, he was heir to a