Lord Caithness served as a House of Lords government-whip under
Margaret Thatcher from 1984 to 1985. He then moved to the
Department of Transport as a
Parliamentary Under Secretary of State, serving until 1986, the year when he became
Minister of State at the
Home Office. In 1988, he was once appointed Minister of State at the Department of Environment. In 1989, he became
Paymaster General and a Minister of State in
the Treasury. In 1990, Caithness was appointed Minister of State at the
Foreign Office, and then, in 1992, back to the
Department of Transport. He was made a
privy counsellor in 1990. With the passage of the
House of Lords Act 1999, Caithness, along with most other hereditary peers, lost his automatic right to sit in the House of Lords. He was, however,
elected as one of the 90 representative peers designed under the provisions of the act to remain in the House of Lords. According to the
Electoral Reform Society, he has since blocked further reform of the Lords, tabling 'wrecking' amendments to a draft Bill to abolish by-elections for hereditary peers, proposed by
Lord Grocott in 2018. Caithness is an opponent of
fractional-reserve banking. Caithness was a trustee of Queen Elizabeth Castle of Mey Trust, from its inception in 1996 until 2016. In 1999, he helped found a heritage charity, the Clan Sinclair Trust, the aim of which is the preservation and conservation of Castle Sinclair Girnigoe, near Wick in Caithness. He serves as chief executive and has been responsible for getting the castle listed by the World Monuments Fund in its Watch List of the 100 Most Endangered Sites in the World in 2002, the fundraising and overseeing the remedial works which has allowed the castle to be accessible and open to the public. ==Marriages and children==