Walston married Catherine Crompton in 1935, in the USA. Oliver Walston, a farmer and agricultural writer, is their second son. From 1946 Catherine was the mistress of the author Graham Greene, who was also her godfather. Walston demanded that the adulterous relationship should cease after the 1951 publication of The End of the Affair, Greene's roman à clef; but it continued, ending by about 1966. After Catherine's death, Walston married Elizabeth Scott, who had previously been the wife of Nicholas Scott. Press reports that Betty Boothroyd, who acted as Walston's secretary before herself entering politics, had been his mistress and also cared for his six children by Catherine, were the subject of a successful libel case brought by Boothroyd.
Walston served in the First Wilson ministry, as Under-Secretary of State for Foreign Affairs from 20 October 1964to the beginning of 1967. In internal Foreign Office discussion, Walston supported James Cable's line, that the USA should cut its losses in the Vietnam War, and argued that the UK should have a pro-active policy of seeking peace. By the second half of 1965 Walston was in fact pushing this line harder than Cable himself. In June 1966 Walston was passing through South Vietnam on an envoy mission, when he was contacted by Janusz Lewandowski, who said he was acting for the Polish government and attempting to find peace in the Vietnam War. Walston, however, treated this as a freelance approach. Following Rhodesia's Unilateral Declaration of Independence Walston was envoy to Portugal, attempting to negotiate an end to sanction-breaking pumping of oil to Southern Rhodesia via Beira, Mozambique. His diplomacy was overtaken by Security Council resolution 221 of 9 April 1966. As a Foreign Office junior minister, Walston argued that the UK government should not grant Rhodesian independence except on terms of majority rule. While Rhodesia was the responsibility of the Commonwealth Relations Office, he maintained that UDI had increased the chances of communist penetration in Africa and that this was a proper concern of the Foreign Office. During this time at the Foreign Office, Walston was a trustee of one of John Collins's secret Christian Action trusts, channelling funds to the African National Congress. He expressed very positive feelings about Fidel Castro. Walston was then Parliamentary Secretary to the Board of Trade, in 1967.
Later political life
On a lecture tour of South Africa in 1968, Walston had private discussions with B. J. Vorster, and as a consequence attempted to open a channel of communication to Kenneth Kaunda. He also visited Nelson Mandela on Robben Island, concluding that the prisoner Mandela was being well treated. At this period the South African government wished to broker a deal between the UK and Ian Smith, and to use Walston's contacts. Walston was a member of the Council of Europe between 1970 and 1975, and a Member of the European Parliament from 1975 to 1977. In the period from 1970 to 1976 Labour politicians met in his apartment in The Albany, forming a retrospectively-christened "Walston group" of pro-European MPs. Walston joined the Social Democratic Party in 1981. During the eighties, Walston became active with the UN accredited non-governmental organisation Agri-Energy Roundtable and served as vice chairman for several years.
Pamphlets
Walston published political pamphlets on agricultural topics:
From Forces to Farming. A Plan for the Ex-Service Man, Liberal Party Publication Department; as prospective Liberal Party candidate for King's Lynn.
