Marquess of Downshire

Marquess of Downshire is a title in the Peerage of Ireland. It was created in 1789 for Wills Hill, 1st Earl of Hillsborough, a former Secretary of State. Hill had already been created Earl of Hillsborough and Viscount Kilwarlin of County Down in the Peerage of Ireland in 1751 with remainder, in default of male issue of his own, to his uncle Arthur Hill, 1st Viscount Dungannon. He was further created Lord Harwich, Baron of Harwich, in the County of Essex, in the Peerage of Great Britain in 1756 with a seat in the House of Lords. In 1772 he was further ennobled as Earl of Hillsborough and Viscount Fairford in the County of Gloucester in the Peerage of Great Britain.

Downshire was the eldest son of Trevor Hill, who had been created Viscount Hillsborough and Baron Hill of Kilwarlin of County Down, in the Peerage of Ireland in 1717, with remainder, in default of male issue of his own, to the male issue of his father, Michael Hill. Trevor Hill was the brother of the aforementioned Arthur Hill, 1st Viscount Dungannon.

Among many other estates, the Marquess owned Hillsborough Castle, the Blessington Estate in Co. Wicklow and Easthampstead Park near Bracknell. The Marquesses are also Hereditary Constables of Hillsborough Fort.

Prior to the passage of the House of Lords Act 1999 the Marquesses sat in the House of Lords as the Earls of Hillsborough.