A High Court judge is expected to rule today on whether Jeremy Corbyn is automatically on the ballot paper in the Labour leadership election.

The senior judge will decide on a claim by a Labour donor that the party “misapplied” the rules when its ruling body granted Corbyn a place in the contest without the need to seek a fresh round of nominations from 51 MPs and MEPs.

Mr Justice Foskett will respond to the writ put forward by Michael Foster, a former parliamentary candidate, after Labour’s national executive committee (NEC) used a marathon meeting to vote 18-14 to give Corbyn the right to compete for his position without the mammoth task of gaining nominations from 20 per cent of the parliamentary party and its equivalent in Brussels.

A ruling that Corbyn did in fact need the new nominations could throw the contest into chaos. Corbyn would be likely to demand the election be put on hold.

Corbyn’s camp were highly confident going into the case that their man would emerge triumphant. The result is listed to come some time after 2pm.

Tom Watson, Labour’s deputy leader, has called the challenge “unhelpful”.