A YouGov poll found that 39 per cent of adults thought that Theresa May was the best choice for prime minister; 25 per cent preferred Jeremy Corbyn

Labour’s position in relation to the Tories slid backwards in almost half the 50 most marginal constituencies where all councillors were up for election last week, analysis by a party insider has found.

The study obtained by The Times shows that in 20 of the Westminster seats examined, the position of Jeremy Corbyn’s party in relation to the Tories declined between 2014 and last week. Labour’s performance against the Tories increased in 23 Westminster seats.

A report accompanying the analysis concluded: “Overall these results are slightly worse than 2014 and nowhere near the level that oppositions have recorded before winning general elections.

“Labour will need to improve significantly in the non-metropolitan marginals to have any realistic chance of a majority in a future election.”