Complex sentence: It was only after the 1964 General Election that their numbers were drastically reduced and by 1966 there were only four left-and only two of these had been elected with the'National Liberal' label.
Split into simpler sentences: It was only after the 1964 General Election that their numbers were drastically reduced, and by 1966, there were only four left. Only two of these had been elected with the'National Liberal' label.