Complex sentence: He was re-elected in the 1975 election, the 1978 election, and the 1981 election, but at the 1984 election, the Labour Party refused to reselect him as their candidate.
Split into simpler sentences: He was re-elected for Labour in the 1975 election, the 1978 election, and the 1981 election. Before the 1984 election however, the Labour Party deselelected him as their candidate.