Senior Labour officials are desperately seeking an answer to the question: Who owns the name "the Labour Party" and who controls its assets?
They want to find out who is legally entitled to the lease on its London headquarters and its regional offices, and also the party logo.
The question of proprietorship is becoming more urgent as the prospect looms of the Labour Party being split in two by the stand-off between the leader, Jeremy Corbyn, and the majority of Labour MPs.
One official said: “Who owns the logo, and the headquarters? Does it all belong to the Leader, as a sort of head of the family, or the General Secretary, or the national executive?
"You would think that this had been settled after the last split but it wasn’t.”
Labour’s deputy leader, Tom Watson, has been in emergency talks with union leaders today in the hope that they can thrash out a compromise that would end the crisis in the Labour leadership that has dragged on for 10 days..
During a face-to-face meeting with Len McCluskey, leader of Britain’s biggest union, Unite, the two men set out their respective positions, then adjourned after agreeing they would meet again. Mr Watson is also speaking by telephone to other union leaders.
But the prospect of an agreement is remote, because the unions heads insist that any deal must be on the basis that Jeremy Corbyn retains his position as Labour’s elected leader, while Mr Watson has told them that the parliamentary party’s ‘red line’ is that Mr Corbyn must go.
If the talks fail, it is increasingly likely that Mr Corbyn will face a leadership challenge. The former shadow Business Secretary Angela Eagle, who is trusted by fellow Labour MPs, is seen as the person most likely to take him on.
There is a dispute over whether Mr Corbyn would have the automatic right to be a candidate if challenged, but assuming he stands, he would have a strong chance of being re-elected by Labour Party members and supporters.
His re-election would make a split in the party almost inevitable, since Labour MPs have voted by 172-40 that they have no confidence in his leadership.
The two sides could then be locked in a protracted legal dispute over the ownership of party assets. That issue did not arise when the Labour Party last split, in 1981, because the four ex-Cabinet minister who broke away to form the short-lived Social Democratic Party made it clear that they were leaving the Labour Party.
The MPs’ position hardened after an impassioned speech at the weekly meeting of the parliamentary party last night by Labour's former leader Neil Kinnock.
Many of the MPs credit Lord Kinnock with rescuing the party from its worst post-war defeat in 1983, but Mr Corbyn’s supporters regard him as a loser who led the party through two election defeats.
One witness said: “Neil Kinnock was amazing. He was like a Welsh whirling dervish. It was genuinely sensational. He got a two-minute standing ovation.
"There were people in tears – but you have to be in tears now. If you’re a Labour MP and you don’t cry, you’re not doing your job.”