Footage shows anti-Corbyn Labour MPs' exit poll reactions as they realise he has increased vote by 10%

Footage has revealed the moment Labour MPs critical of Jeremy Corbyn found out their party was not heading for the election defeat they predicted, but instead had seen its poll ratings increase by 10 per cent.

Previously unseen video of the time the General Election exit poll was released on 8 June shows a number of those opposed to the Labour leader expressing shock and disbelief at the result.

The footage was filmed as part of a BBC documentary, titled Labour: The Summer that Changed Everything, due to be broadcast on Monday night.

Lucy Powell, the former Shadow Education Secretary who had claimed Mr Corbyn was “unable to command the support of the country”, is seen gasping as projections show the Conservatives will be the largest party but fall short of an overall majority.

“Largest party – oh my God”, she says. “Oh my God, that’s unbelievable. Oh my God. That’s 30 seats gain.”

Other Labour MPs display a similar level of surprise as BBC anchor David Dimbleby announces that Theresa May appeared to have squandered her parliamentary majority.

Brentford and Isleworth MP Ruth Cadbury is shown sitting agape while watching the result. “Oh my God”, she, too, says.

As news breaks that Labour has won seats at the Conservatives’ expense, Stephen Kinnock, Labour MP for Aberavon, looks stunned and says: “We’re looking at a hung Parliament then”.

He continues to stare at the screen, apparently lost for words.

Many Labour MPs had expected that Labour would lose the election and Mr Corbyn would be forced to resign as leader.

Instead, the party’s vote share increased by 9.6 per cent and it gained 30 seats.

The unexpected result strengthened Mr Corbyn’s standing and forced many of his fiercest critics to accept he had defied predictions.