Tories and Labour on course for lowest share of the vote since 1945

Poll reveals historically low support for the big two, with smaller parties up by five points

Labour and the Tories are on course for their lowest combined vote share since the second world war, as the latest Opinium poll for the Observer shows a shift away from the main parties.

With all the parties having now unveiled their election manifestos, Labour has maintained a dominant 17-point lead over the Tories with less than three weeks to go until polling day. However, Reform and the Lib Dems are up two points each.