The Rockefellers also had an interesting link with the UK wartime Prime Minister. Searching for a biographer to chronicle their family heritage in the 1930s, they approached Winston Churchill, who was well-known for his writing talent and penned 42 books in his lifetime. Yet Churchill’s request of $250,000 for the task – equivalent to around $4.7 million (£3.8m) today – was too steep, so they ultimately got a Columbia University historian to do it instead.

Read From Rockefellers to Rothschilds: how five old-money dynasties live today

How the rich lived in the Second World War