The Washington summit was useful to Lyndon B. Johnson mainly because it allowed him to impress upon the British the need for them to retain their traditional 'great power' role and also to allow him to bring the multilateral force (MLF) to a conclusion. Harold Wilson accepted the American view that Britain should preserve its current position in defence, telling the Cabinet on 11 December that 'the most encouraging fact about the conference was America's emphasis on Britain's world wide role'. Johnson not only wanted Wilson to maintain Britain's defence commitments, but to extend them into South Vietnam. After Wilson's visit to Washington, most observers, including the President, anticipated that he would face a serious challenge in explaining what he had agreed to in Washington to the House of Commons in the foreign affairs debate scheduled for 16-17 December.

From January to April 1965 the character of the Harold Wilson-Lyndon B. Johnson relationship traversed the spectrum from discord to cordiality. Discord erupted over the Vietnam War when Wilson telephoned Washington in the early hours of 11 February to suggest to Johnson an urgent visit to the White House. Wilson agreed to the US initiative, even though the visit might have caused a political storm in Britain had it become public knowledge - it would appear that the United States was dictating British economic measures. Wilson noted that unlike the December summit and the telephone conversation in February, Johnson did not make 'any suggestion of our committing troops to Vietnam nor even any reference to police, medical teams, or teams to handle the flow of refugees'. On 10 April, Patrick Dean advised that to help strengthen the Anglo-American relationship, Britain should provide more support for the United States in Vietnam.