The ComRes survey for The Independent, carried out on the eve and the day of the Glasgow East defeat, showed the party now enjoyed the support of fewer than a quarter (24%) of voters.

It was a point down on last month. David Cameron's Conservatives and Nick Clegg's Liberal Democrats were unchanged on 46% and 18% respectively, and "others" were up one point.

The result would translate into a 236-seat landslide Commons majority for the Tories if repeated at a general election.

:: ComRes telephoned 1,021 adults and the results were weighted.