JEREMY Corbyn’s closest ally threw open the option of holding a second referendum yesterday- as Labour’s Brexit policy all-but collapsed.

Marxist Shadow Chancellor John McDonnell became the second frontbencher this week to say a vote on the final Brexit deal must not be ruled out.

He said it wasn’t currently Labour party policy to have another referendum.

But Mr McDonnell added: “We recognise that when the Government comes forward with its proposals - and I’m worried we might be in a no-deal situation, Parliament will decide the next step.

So we’re not saying any options [are] off the table when that debate happens.”

But he said his fellow frontbencher Barry Gardiner was right to warn earlier this week that a second referendum could risk sparking riots on the streets.

Mr McDonnell’s refusal to rule out a second referendum will escalate fears that Labour is preparing to soften its stance on Brexit even further.

Earlier this week Labour’s Shadow Brexit Secretary Sir Keir Starmer said a second referendum should be “on the table” if Theresa May fails to get a deal before next March.