The difference between results is similar to a preliminary survey which asked people who they thought would win, with 33 percent in favour of Boris Johnson and 28 percent in favour of Jeremy Corbyn.
The latest debate comes as another win for Boris Johnson, who according to more data from YouGov has had a consistently slim lead in television debating.
In November, when the leaders had their first debate on ITV, YouGov asked people who they believed performed best on television.
Their snap analysis of 1,646 people found 51 percent believed Boris Johnson performed best, while 49 percent favoured Jeremy Corbyn.
