Complex sentence: It is the biggest and most successful socialist party in modern Scottish politics; following local and parliamentary elections in 2003, the party had six Members of the Scottish Parliament (MSPs) and two councillors.
Split into simpler sentences: It is the largest and most successful socialist party in modern Scottish politics. The height of it's electoral success was the local and parliamentary elections in 2003, when the party elected six Members of the Scottish Parliament (MSPs) and two councillors.