Although the Liberal Party had been founded in the 19th century, the Liberals were squeezed out of party politics by Labour in the first third of the 20th century and did not have enough seats in parliament to qualify as 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 1963 to 2000 says:

Until the 1920s, the Liberals were one of Britain's two main parties, when they were displaced by Labour. In 1974 the Liberals won nearly a fifth of the vote. In 1983 and 1987 they arranged an electoral pact with the newly formed party Social Democratic Party (SDP, which had split from the Labour Party). In 1988 the two parties (the Liberals and the SDP) merged in one party called the Liberal and Social Democrats, led by Paddy Ashdown. However, the SDP leader, David Owen, opposed the merger and continued rallying with the SDP banner until 1992, when the SDP disappeared. The Liberal and Social Democrats contested the 1992 election as the Liberal Democrats and pushed their advocacy of governmental reform. "They seek to make government more effective and responsive by devolving many powers and functions to a new tier of regional governments … and by changing the electoral system to proportional representation" (Rasmussen and Moses, 1995: 136). Education was a major issue in their 1992 electoral campaign, advocating to reduce class size, buying more books and equipment and constructing new buildings.

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.