Example UK Politics Essay: is voting behaviour in by-elections unpredictable?

A by-election occurs when an MP needs to be replaced between General Elections – this can be due to the death or resignation of the MP, or if the MP becomes bankrupt or is convicted of a criminal offence. Occasionally by-elections are triggered by the defection of the incumbent MP to a different party e.g. Mark Reckless, former MP for Rochester, defecting from the Conservatives to UKIP in 2014, resulting in the 2^nd largest party swing ever in a by-election as he was re-elected (although subsequently lost in the 2015 General Election)