Complex sentence: Another general election was called for October 1974, which gave the Labour party a slim majority in Westminster, whilst the SNP recorded 30% of the Scottish vote, their best ever result at that time.
Split into simpler sentences: Another general election was called for October 1974, which gave the Labour party a slim majority in Westminster. The SNP recorded 30% of the Scottish vote in the October election, their best ever result at that time.