As an artillery officer in the Buckinghamshire Yeomanry, he served with the British Expeditionary Force in France, the North African Campaign and in Italy with the 77th Field (Highland) Regiment before becoming a major in the newly formed Jewish Infantry Brigade.
Tutored by his uncle Anthony Gustav de Rothschild, he played a key role in the continuing success of the bank, and became its chairman from 1970 to 1975.
In 1998, he appeared in the Chuck Olin documentary film titled In Our Own Hands that told the story of the only all-Jewish fighting force in World War II.
Like other members of the Rothschild family, he was an art collector, but the maintenance and development of the Exbury gardens was his most important pastime.
In 2005, the Royal Horticultural Society bestowed on him the Victoria Medal of Honour, the highest accolade in the British gardening world.