Clacton-on-Sea's MP Douglas Carswell resigned from the Conservative party to join UKIP, triggering a by-election nine months before the next general election.
Who is this former Tory backbencher and what does he stand for?
Douglas Carswell is a vocally eurosceptic, libertarian politician heavily in favour of a more local style of Government.
He openly criticised ID cards and the quality of equipment given to troops in Afghanistan.
Carswell lead the campaign to eject the then-Speaker, Michael Martin, for his role in the expenses scandal which rocked Westminster in 2009.
In order to force Martin out of his position, Carswell broke Parliament rules by openly criticising the Speaker. MPs do not normally voice opinions on the Speaker because the role is meant to be neutral.
Carswell increased his majority in the next election by 12,068 votes, in what was now the constituency of Clacton-on-Sea. He is seeking re-election as a UKIP member.