Moynihan followed his father in taking the Liberal Party whip in the House of Lords. By 1947, he was the treasurer of the party, and commented that he believed that the Labour Party's social reforms were close to the spirit of the Liberals, but that they ignored the individual. In 1949, he became the party chairman. His time as chairman was dominated by the 1950 general election, and a dispute with the Conservative Party, who ran National Liberal Party candidates under the label "Liberal and Conservative". In February 1950, an object hit Moynihan's car while he was driving in Epping Forest. He claimed that it might have been a bullet, although he was unable to prove this. In 1950 and 1951, Moynihan served as President of the National Union of Liberal Clubs, and he again became the party treasurer. Long a friend of Edward Martell, in 1956 Moynihan was a founder member of his People's League for the Defence of Freedom, which claimed to combat the "tyranny of trade unions". The new organisation was opposed by the Executive of the Liberal Party, which was concerned that it was contemplating standing rival political candidates, and also opposed its calls for strikebreaking. The People's League became the National Fellowship, which opposed immigration and entry to the Common Market. Because of his support for the new organisation, in 1962, Moynihan was removed as a vice-president of the Yorkshire Area Liberal Federation. In 1963, Moynihan resigned from the Liberal Party, citing his membership of Martell's latest organisation, the Freedom Group, which actively supported Conservative candidates. However, in 1964, he began disassociating himself from Martell, resigning his posts in Martell's organisations by early 1965.
Marriages & Children
Lord Moynihan married firstly Ierne Helen Candy on 8 April 1931. They had the following children:
Hon Imogen Anne Ierne Moynihan, married firstly Michael Edward Peter Williams on 3 September 1953, later divorced. She married, secondly, Charles Ivan Vance on 23 April 1965.
Hon Juliet Jane Margaretta Moynihan, married firstly Thomas Edwin Bidwell Abraham on 25 July 1958. She married secondly Harry Hougham Sparks in 1978.
In April 1965, Lord Moynihan was charged with "persistently importuning for an immoral purpose". He was taken ill and died aged 58 on 30 April, a few days before he was due to appear at Bow Street Magistrates' Court. He was succeeded in the barony and baronetcy by his elder son Antony.