Complex sentence: He was elected to Dumbarton Burgh Council in 1958 and as Provost of Dumbarton in 1962 and 1965, and in 1968 was re-elected unopposed for an almost unprecedented third term.
Split into simpler sentences: He was elected to Dumbarton Burgh Council in 1958 and was first elected as Provost of Dumbarton in 1962. In 1968 was re-elected unopposed for an almost unprecedented third term.