He was succeeded by his son Lawrence Mark Dundas, 4the Marquess of Zetland.
He represented Richmond and Stirling in the House of Commons and also served as Lord Lieutenant of Orkney and Shetland.
Charles Cornwallis, 1st Marquess Cornwallis | Robert Gascoyne-Cecil, 3rd Marquess of Salisbury | Marquess | Francis Rawdon-Hastings, 1st Marquess of Hastings | Richard Wellesley, 1st Marquess Wellesley | Marquess of Bute | Wills Hill, 1st Marquess of Downshire | James Broun-Ramsay, 1st Marquess of Dalhousie | David Cecil, 6th Marquess of Exeter | 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 | Victor Hervey, 6th Marquess of Bristol | Robert Wynn Carrington, 1st Marquess of Lincolnshire | Marquess of Rockingham | Marquess of Lansdowne | marquess | John Neville, 1st Marquess of Montagu | Freeman Freeman-Thomas, 1st Marquess of Willingdon | Paul Marquess | Marquess of Milford Haven | Marquess of Anglesey | Marquess of Ailsa | John Hamilton-Gordon, 1st Marquess of Aberdeen and Temair | Zetland | William Parr, 1st Marquess of Northampton | Victor Hope, 2nd Marquess of Linlithgow | Marquess of Sligo | Marquess of Salisbury |
In 1970, Scully was married to Lady Carolyne Christie, the niece of the Marquess of Zetland.