Frederick Howard was elected a Knight of the Thistle in 1768. Two years later he married Margaret Caroline [d. 1824], daughter of the 1st Marquess of Stafford. Howard was a Privy Cousellor and Lord Lieutenant of Ireland (1780-82). He was installed as a Knight of the Garter in 1793. The Howards had three sons and three daughters; son George succeeded his father as 6th Earl. Around 1778, Howard commissioned Sir Joshua Reynolds to paint his daughter; this portrait now in NGA (1937.1.106). [Compiled from sources and references recorded on CMS]
Brigstocke, Hugh. William Buchanan and the 19th Century Art Trade: 100 Letters to His Agents in London and Italy. New Haven, 1982: 464.