Leadership result is a 'big moment' in Labour history

Yvette Cooper, Jeremy Corbyn, Liz Kendall and Andy Burnham have been campaigning for three months

Whatever the result of the Labour leadership contest there's no disguising how big a moment this is in history of the Labour Party - one which casts the whole future shape both of the party and of Welsh politics into doubt.

If, as the polls suggest, Jeremy Corbyn emerges victorious Labour will have chosen its most left-wing leader since Keir Hardie, the Merthyr MP who died exactly a century ago.

Despite calls for unity from all sides, Mr Corbyn would find it difficult to lead a parliamentary party where he has few supporters and Welsh Labour MPs are no keener on Mr Corbyn than their English colleagues.

On the other hand, a narrow defeat for Mr Corbyn might prove equally traumatic, with a newly enthused left prepared to take the fight to the new leadership over policy-making and parliamentary selections.

While Labour in Westminster have almost five years to sort themselves out before the next general election, in Wales the party faces a crucial contest next May when Carwyn Jones will be defending the record of the UK's only remaining Labour government.

Britain's biggest trade union Unite has announced that it would be backing Mr Corbyn

Carwyn Jones says the assembly election will be a 'Welsh' poll, regardless of who is UK Labour leader

While Welsh Labour will try and distance itself from any turmoil in Westminster during the election campaign, the Conservatives believe they could reap huge benefits from a Corbyn leadership particularly in the eleven Welsh constituencies they won in this year's general election.

Plaid Cymru though might be forced into a tactical rethink over their strategy to outflank Labour from the left.

A Corbyn win would almost certainly increase pressure for a federal Labour Party - a move long supported by many assembly members but viewed with suspicion by Welsh Labour MPs.

Parliamentarians horrified at the prospect a Corbyn leadership may well support a more autonomous Welsh party to put some distance between themselves and the new leadership.