Complex sentence: Since then, however, the Conservative majority has substantially increased, exceeding 28,000 in 2015; however since Haveron was suspended from the Lib Dems after nominations and no other candidate was on the ballot this majority is likely to be an anomaly.
Split into simpler sentences: Since then, however, the Conservative majority has substantially increased, exceeding 28,000 in 2015. However since Haveron was suspended from the Lib Dems after nominations and no other candidate was on the ballot this majority is likely to be an anomaly.