Theresa May's Conservatives have extended their poll lead over Labour to 18 points, according to a new poll.

The ICM poll for The Guardian - released days ahead of crucial by-elections in Copeland and Stoke Central - put Tories on 44% nationwide (up two points since a similar survey two weeks ago) and Labour on 26% (down one).

The Tories have enjoyed a larger lead in just three polls in this series, which dates back to 1983, said ICM.

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Two of these came shortly before the 1983 general election, when Michael Foot went down to a crushing defeat at the hands of Margaret Thatcher, and the other at a low-point in Gordon Brown's premiership in 2008.

Labour's support was just one point above its worst ratings in the series - 25% in June 2008 and August 2009. But Conservatives remain below their peak of 47.5% recorded in 1983.

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Ukip was up one point on 13% and Liberal Democrats down two on 8%, while Greens were unchanged at 4%.

:: ICM Unlimited interviewed 2,028 adults between February 17 and 19. 2017.