Nearly half of Labourvoters are prepared to desert the party putting the Conservatives on course for an even bigger victory than forecast, a poll has found.

Yougov said that 48 per cent of Labour's voters are either planning to switch their allegiance to another party or are undecided about whether to back Jeremy Corbyn.

The EU referendum had caused a "significant realignment" in British politics with Labour facing a "dramatic" drop in its support as Leave voters back the Tories and Remain voters back the Liberal Democrats.