Viscount Thurso, of Ulbster in the County of Caithness, is a title in the Peerage of the United Kingdom. It was created in 1952 for the Scottish Liberal politician and former Secretary of State for Air, Sir Archibald Sinclair, 4th Baronet. His son, the second Viscount, served as Lord Lieutenant of Caithness from 1973 to 1995. As of 2009 the titles are held by the latter's...