Complex sentence: After years of austerity, the British economy was on an upswing in 2015, When Prime Minister David Cameron called the United Kingdom general election, 2015 for 7 May 2015.
Split into simpler sentences: After years of austerity, the British economy was on an upswing in 2015, When Prime Minister David Cameron called a general election. The United Kingdom general election, 2015 was held on 7 May 2015.