If Jeremy Corbyn leads Labour into the next election, the party will be defeated "to the same level as in 1931", Neale Coleman, who was Corbyn's first head of policy, has warned.

The remarks where made to party members at a nomination meeting in Islington North, Corbyn's constituency, where Coleman is also a member. Coleman told activists that he was "delighted" to vote for Corbyn last summer and to be appointed as policy head, but that his experience in the leader's office had taught him that Corbyn was not suited to lead the Labour Party.

Saying that "all of us know the Tories are going to call an election next May", Coleman warned the meeting that with Corbyn at the helm, the party would go down to a defeat of "the same level as in 1931". In 1931, Labour was reduced to 52 seats.

But a senior Labour source hit back against the remarks, describing Coleman's tenure as policy chief as a "mistake from start to finish", saying that he was "just bitter because of the way it ended". "He was simply not cut out for the job. Neale has many attributes but he was not a head of policy as even Sadiq Khan realised".

Islington members went on to endorse Corbyn for the leadership, as they did in 2015. One attendee described the mood as "a shitshow".

Coleman, who worked for Ken Livingstone and Boris Johnson, quit Corbyn's office in January 2016. He has since taken a job working on Owen Smith's campaign.