The Labour Party was one of the original parties in Janda's 1950-1962 ICPP study. The party continued throughout 1950-1990 in the Harmel-Janda study of party change.

The essay on party politics in the United Kingdom from 1950 to 1962 says:

The British Labour Party emerged from the role of Loyal Opposition in 1964, when electoral success brought a Labour government under Harold Wilson. Wilson's government increased its majority in the 1966 elections but was defeated in 1970. In February 1974, Labour won a bare plurality and Wilson formed a minority government until his party won a narrow majority of seats in the October elections later that year. In 1976, James Callaghan succeeded Wilson as party leader and thus became prime minister in a Labour government. Losses in by-elections reduced the Labour majority to one seat in October 1976, and early in 1977 Labour entered an agreement with the small Liberal Party for votes to remain in office. Dependent upon such tenuous support, Callaghan and Labour clung to government throughout 1978. Defeated on a vote of confidence in March 1979, Labour was forced to call an election and was defeated at the polls in May.

The essay on party politics in the United Kingdom from 1963 to 2000 says:

The Labour Party led British government on three occasions since 1963. In 1964, Harold Wilson became Prime Minister when Labour won the 1964 elections with a slim majority, but Labour lost to the Conservatives in 1970. The Labour Party won the 1974 elections again by a narrow margin, returning Harold Wilson as prime minister. But splits in the party over membership in the European Economic Community (which Wilson favored, but more radicals members of his party and powerful unions opposed) and a failing economy led to Wilson's resignation in March of 1976, to be succeeded by James Callaghan. During his term in office (April 1976 to May 1979), Callaghan had to negotiate agreements of support from the small Liberal Party (that by then had thirteen seats in Parliament) and even from the Welsh and Scottish separatist members of Parliament.

Consult the index to variables for annual scores of the party's issue orientation, organizational complexity, centralization of power, and coherence from 1950 through 1990.