Complex sentence: It nominated candidates in the UK general election, 1929, and most elections in the late 1950s to the early 1970s, but then suffered the loss of many of its members to the Alliance Party of Northern Ireland.
Split into simpler sentences: It nominated candidates in the UK general election, 1929, and most elections in the late 1950s to the early 1970s. After 1970 it suffered the loss of many of its members to the Alliance Party of Northern Ireland.