He was Lord Clerk Register of Scotland, 1768–1816; Member of Parliament (MP) for Glasgow Burghs (1761–1780) and for Argyllshire (1780–1799).

Lord Frederick was educated at Westminster School (1743-6) and Christ Church, Oxford (1747) before entering Middle Temple (1751) and being called to the Bar in 1754.

In 1774 Lord Frederick had laid the foundation-stone for a register house at Edinburgh, and procured a permanent establishment for keeping the records, and received the thanks of the court of session.

Lord Frederick sat in the Irish House of Commons for Thomastown from 1767 to 1768 and for St Canice from 1768 and 1776.

[4] In 1786 a member of the board of control for India, and from 1787 to 1793 the joint Vice-Treasurer of Ireland under George, Viscount Townshend, the Lord-lieutenant.