Opposition parties hope to overturn government majorities in three constituencies vacated by Tory MPs amid controversy

Polls have opened in three parliamentary seats where byelections are being held, with Rishi Sunak braced for an electoral test of his premiership.

The Conservative-held constituencies are being targeted by Labour and the Liberal Democrats, who hope to overturn large majorities and send Tory MPs off into the summer recess nervous about their own political futures come the general election.