Clacton by-election: Nigel Farage claims victory for Ukip would be 'shift in tectonic plates of British politics'

Voters going to the polls today in a double by-election in Clacton, Essex, and Heywood and Middleton, Lancashire

Nigel Farage unveiling his party's latest campaign poster (Reuters)

Victory for Ukip in the Clacton by-election today would signal "a shift in the tectonic plates of British politics", Nigel Farage has claimed.

Voters were today going to the polls in by-elections in Clacton, Essex, and Heywood and Middleton, Lancashire, with Ukip hoping to gain its first elected MP.

Douglas Carswell, who defected to Ukip from the Tories, is the favourite to retain his Clacton seat in the by-election, triggered when he stood down as he changed parties.

Ukip has also been campaigning heavily in Heywood and Middleton, where a by-election was triggered by the death of Labour MP Jim Dobbin who had held the seat since 1997.

Ukip leader Mr Farage told The Telegraph that while victory in Clacton would be a "shift in the tectonic plates of British politics", a win in both seats would be "Krakatoa".

While the Tories go into the Clacton vote as underdogs, Prime Minister David Cameron has insisted his party could win.

Mr Carswell held the seat with a majority of more than 12,000 at the 2010 general election and is expected to benefit from a strong personal following.

A strong challenge from Ukip candidate John Bickley is expected in the Heywood and Middleton by-election, although opinion polls put Labour candidate Liz McInnes comfortably in the lead.