Jeremy Corbyn may be popular across all parties, but there's one crucial catch for Labour

Eyebrows were raised on Friday afternoon as it emerged that Jeremy Corbyn was the most popular Labour leadership candidate among voters from other political parties.

A YouGov poll for the Evening Standard showed that the left-winger was by far the most popular choice among Liberal Democrat and Ukip voters and was only narrowly behind Andy Burnham among Conservatives.

Overall, 46 per cent of those who expressed an opinion in the poll (i.e. excluding "don't knows") supported Corbyn.

The paper said the poll was proof that Corbyn's appeal stretched beyond left-wingers and trade unionists - a criticism many of his opponents have been claiming until now.

One problem with the poll, however, is that it only focuses on London voters, which some have suggested is not a reliable bellwether for the rest of the country anyway.

However, there is one crucial, damning problem for Labour's hopes of winning the next election - which can be seen on the far right of the chart below:

The percentage of those choosing "none of these" outweighed each of the four candidates in each party other than Labour.

If Labour wants to win the next election, it's going to need to win back voters from other parties. If this poll is anything to go by, this leadership election could be a complete waste of time.

More: Here's what Labour would actually look like under Jeremy Corbyn