Complex sentence: The Westminster Labour government had initially designed the additional member system to make it impossible for one party to win an outright majority, but the SNP won enough seats from the other parties to take 69 seats, a majority of four.
Split into simpler sentences: The Westminster Labour government had initially designed the additional member system to make it impossible for one party to win an outright majority. However, the SNP won enough seats from the other parties to take 69 seats, a majority of four.