Ukip's hopes of a significant breakthrough at the general election have been dealt a blow by polling showing it is not on course to win any of a series of key target seats. Detailed constituency polling commissioned by Lord Ashcroft in Ukip targets found the party behind the Conservatives in all of them. They include Boston and Skegness, where Ukip won its biggest majority in last year's council elections. Scroll down for video Polling by Tory peer Lord Ashcroft in four Ukip target seats found the party behind the Tories in all of them Ukip Leader Nigel Farage receives a Whitstable Bay Beer from local landlady Aileen O'Leary during a walkabout in Sandwich, Kent
@highlight
Polls by Tory peer Lord Ashcroft show Ukip trailing in four target seats
@highlight
Party is behind in Ukip stronghold of Boston and Skegness, Lincolnshire
@highlight
Ukip is also trailing in key seats in  Cambridgeshire, Essex and Kent
@highlight
Ukip's vote is likely to be squeezed between now and May, pollsters believe
In North East Cambridgeshire, where the @placeholder have also been alarmed by Ukip's success in local elections, the party is a commanding 21 points ahead.