Jonathan Guinness was educated at Eton College and the University of Oxford. He worked as a journalist and then as a merchant banker. From 1970 to 1974 he was a Leicestershire County Councillor.
Lord Moyne twice stood as Parliamentary Candidate for the Conservative Party, including the Lincoln by-election of 1973, notable for the election of Dick Taverne.
He was a long-standing and early member of the Conservative Monday Club, serving on several of its committees. He was a member of the Club's Executive Council in 1971, when he became Chairman of their 'Action Fund', and elected National Chairman on 5 June 1972, fighting off challenges from Richard Body MP, and Timothy Stroud. The Guardian and The Times referred to his election as "a right-wing victory". At the Club's Annual General Meeting in April 1973 Guinness retained the Chairmanship for another year, defeating George Kennedy Young. In mid-1974 he was invited to address Conservative students at Portsmouth Polytechnic, but was prevented from doing so by protesters.
On 10 October 1989, at the Conservative Party Conference, he chaired a controversial fringe meeting organized by the Young Monday Club, advertised as The End of the English? - Immigration and Repatriation. The other speakers were MPs Tim Janman and Nicholas Budgen.
As Chairman of the Club's Race Relations & Immigration Committee, he also wrote the same month to all Club members; "There has been a lot of ill-thought out agitation following events in China, urging the government to amend the British Nationality Act so as to give the right of UK residence to more than three million people from Hong Kong who hold British passports. At the time of writing the government has stayed firm on this, but it is under pressure. If you have not already done so, please write to your M.P., your local and national newspapers, or the Prime Minister expressing support for the government's stand. Remember, a passport is not a residence permit, but a travel document; and think of the sheer physical burden of housing and accommodating a sudden influx of this size."
He was also Club Vice-Chairman until late 1990 when he was replaced by Andrew Hunter, MP.
Lord Moyne was accused of involvement in a Swedish financial scandal. The case concerns a now defunct Swedish investment company, Trustor, of which Lord Moyne was made a figurehead director. It was alleged that Guinness was involved in the disappearance of £50,000,000 from Trustor's accounts, £35,000,000 of which were soon found on Trustor AB:s own bank account as they had never left the company. Guinness maintained that he was innocent of any wrongdoing, claiming he has been "stitched up". During the proceedings, Swedish authorities were successful in obtaining a freezing order over what little assets he had left. He was found innocent by the Swedish Court. Joachim Posener the allegred mastermind along with Moyne fled the country.
Lord Moyne has spoken in support of the Falun Gong movement in China since it was banned there in 1999, as reported in Hansard.
Lord Moyne was a non-executive director from 1960 to 1988 of the company set up by his family. His book Requiem for a Family Business gives an uninvolved insider's account of the corporate developments leading to the Guinness share-trading fraud.
Lord Moyne has been twice married, with children:1) 1951 (divorced 1963) Ingrid Wyndham (later Lady Kelvedon) who died in 2009 and by whom he had two sons and a daughter.
2) 1964 Suzanne Lisney, later known as Sue, Lady Moyne (d. 2005 of lung cancer), by whom he had a third son and a second daughter.
He also had a mistress, Susan ('Shoe') Taylor (1944–2003), and a further three children by her. To avert a scandal Guinness published Shoe - The Odyssey of a Sixties Survivor in 1989. After which, The Sun newspaper (6 July 1989) ran a double-page article with pictures entitled Always a Mistress - Never the Bride.
Lord Moyne has the following children:By Ingrid:
- Hon. Catherine Ingrid Guinness (b. 1 June 1952), who married 1stly 1983 (divorced 1988) James Donald Charteris, Lord Neidpath (b. 1948), only surviving son and heir of the Earl of Wemyss and March, by whom she has issue 1 son and 1 daughter. She married 2ndly 1990 Robert Fleetwood Hesketh (d. November 2004) by whom she has issue three children, including twin daughters. She worked as PA to Andy Warhol.
- Hon. Jasper Jonathan Richard Guinness (9 March 1954 – 7 May 2011), who was married with two daughters.
- Hon. Valentine Guy Bryan Guinness (b. 9 March 1959), the heir apparent who was married to handbag designer Lulu Guinness, née Lucinda Rivett-Carnac, and has issue, two daughters. They were separated in 2004, and divorced in 2013.
By Susan Taylor
- Hon. Sebastian Walter Denis Guinness (b. 1964) who has been twice married, with no issue.
- Hon. Daphne Suzannah Diana Guinness (b. 1967), socialite, former wife of Spyros Niarchos (b. 1955), by whom she had three children.
- Diana Guinness (b. 1981)
- Aster Guinness (b. 1984)
- Thomas Guinness-Taylor (b. 1986)
Moyne and his daughter, Daphne, both had letters published in the same edition of The Daily Telegraph (16 August 2003) attacking the writer Andrew Roberts over his criticism in the same newspaper on 13 August 2003 of Jonathan's mother, Diana Mitford, following her death.