The party leadership forced the cancellation when it became clear that the NEC wanted to support anti proportional representation campaigners in tomorrow's crucial debate on the voting system.
The NEC embarrassed the Prime Minister last month when its official submission to the Jenkins Commission, which is looking at the issue, came out strongly against reform and complained that proportional representation led to permanent coalition.
However, the prospect of the party's ruling body giving official approval to one side of the increasingly acrimonious row prompted officials at Labour's Millbank headquarters in London to intervene.
The meeting was due to go ahead at 7.30am yesterday, but The Independent understands that party officials panicked and placed notes calling it off under NEC members' hotel doors at 2am.
It also emerged yesterday that the set-piece debate on the issue, tomorrow, will now be as short and low-key as possible under a deal between PR opponents and Mr Blair's aides.
Hardline anti-PR unions such as the T&G, GMB, Unison and MSF wanted a conference vote on the issue, but it became clear that the engineers union, AEEU, did not want to embarrass the Prime Minister.
The motion, which urges Labour to firmly back the first-past-the-post system, was eagerly anticipated by both pro-reform and anti-reform groups.
Party managers were keen to avoid any debate on PR at the conference, but more than 22 constituencies submitted emergency motions on the subject.
Yet as the AEEU is the official mover of the motion, it will have the final say and is likely to remit the motion, to the annoyance of its fellow unions and activists.
Instead, the compromise deal will give campaigners the chance to make their views clear in a brief, tightly regulated debate that will cause as little damage as possible. No vote will be taken.Reuse content