Lockharts held the barony of Lee in Lanarkshire from the 14th century at least, but apart from a few charters this collection dates from the 17th to the early 20th century. The direct line of lairds of Lee, from Sir James, Lord Justice Clerk, and Sir William, Cromwell's ambassador, died out in 1777. Lee then came into the possession of the descendants of Sir James's younger son, Sir George Lockhart, Lord President, who had acquired large holdings of land consolidated into the baronies of Carnwath and Dryden: firstly General James Lockhart, Count of the Holy Roman Empire, whose son died without issue in 1802, and secondly Sir Alexander Macdonald Lockhart, 1st Baronet. With the death without issue of Sir Simon, 5th Baronet, in 1919, the estates passed to a cousin, S F Macdonald Lockhart.