The rise and fall of Ukip has been one of the most extraordinary developments of this Parliament.

In 2010 - when Nigel Farage announced that he was to stand again as leader - it was to a conference hall packed with the party faithful but with little fanfare from the media.

Since then, Ukip's support has consistently grown in the polls - and been a consistent headache for the Prime Minister. The party was widely seen as responsible for forcing his commitment to an EU referendum last year, while the defection of two Conservative MPs has caused him major difficulties this year.

Douglas Carswell became its first elected Westminster MP, and could gain a second next month when fellow defector Mark Reckless seeks re-election in Rochester and Strood.