His mother, Pamela Cobbold of the East Anglian brewing family, died when he was 21 months old.

[4] After his mother's death, his stepmother became Dorothy Mackay, who was banker Marcus Wallenberg's ex-wife.

[1] During World War II, he was sent to live first with the Wallenbergs in Stockholm and later with the Morgans, another banking dynasty, in New York City.

[1][2] He was in charge through interesting but turbulent times, beginning with the stock market and property crash of 1973–74.

[1][2] Hambros was one of the leading banks called in by the Bank of England to launch the financial lifeboat which dealt with the collapse of the Slater Walker empire and generally saved the financial system from collapse.

[1][2][3] His efforts were rewarded with a life peerage, created 26 September 1994; he took the title Baron Hambro, of Dixton and Dumbleton in the County of Gloucestershire.

He had nine grandchildren: Christiana, Tatiana, Charles, Edward, Alexander, Marina, Jemima and Sam.