Hay was a great-grandson of the 2nd Marquess of Tweeddale and in 1787, he inherited the titles of his first cousin once-removed, the 6th Marquess.
Charles Cornwallis, 1st Marquess Cornwallis | Robert Gascoyne-Cecil, 3rd Marquess of Salisbury | Marquess | Charles Lennox, 2nd Duke of Richmond | Robert Devereux, 2nd Earl of Essex | Hugh Grosvenor, 2nd Duke of Westminster | Edward Harley, 2nd Earl of Oxford and Earl Mortimer | 2nd United States Congress | Michigan's 2nd congressional district | 2nd | William Petty, 2nd Earl of Shelburne | William Lamb, 2nd Viscount Melbourne | Hugh Percy, 2nd Duke of Northumberland | Francis Rawdon-Hastings, 1st Marquess of Hastings | Richard Wellesley, 1st Marquess Wellesley | Marquess of Bute | George Villiers, 2nd Duke of Buckingham | Wills Hill, 1st Marquess of Downshire | James Broun-Ramsay, 1st Marquess of Dalhousie | David Cecil, 6th Marquess of Exeter | Charles Cochrane-Baillie, 2nd Baron Lamington | Walter Rothschild, 2nd Baron Rothschild | Thomas Holland, 2nd Earl of Kent | Robert Grosvenor, 1st Marquess of Westminster | Henry Paget, 1st Marquess of Anglesey | Frederick Hervey, 8th Marquess of Bristol | Frederick Hamilton-Temple-Blackwood, 1st Marquess of Dufferin and Ava | Charles Grey, 2nd Earl Grey | Aymer de Valence, 2nd Earl of Pembroke | William Barrington, 2nd Viscount Barrington |