He and his younger brother, John Spencer, were raised to the rank of duke's sons in honour of their late father and styled as lords.

[6][7] During the First World War, Lord Richard served abroad and was wounded and mentioned in dispatches.

During the Second World War, he was honorary colonel of the 56th (King's Own) Anti-Tank Regiment, Royal Artillery.

In December 1908 he was appointed chairman of the Royal Commission on Systems of Election, with the mandate "to secure a fully representative character for popularly elected legislative bodies" and "to consider whether, and how far, they, or any of them, are capable of application in this country in regard to the existing electorate".

[1] In 1911, Cavendish was on Prime Minister Asquith's list of peers in case the Parliament Act 1911 was not passed by the House of Lords.

Cavendish married Lady Moyra de Vere Beauclerk, daughter of the Duke of St Albans, in 1895.