As fellow left-wingers prepared to speak out against the decision at fringe meetings and to demand an emergency conference motion, three shadow cabinet members - David Blunkett, Margaret Beckett and Joan Lestor - surprised the party mainstream by failing to support the 17-5 vote to bar the 31-year-old barrister.
Ms Davies called the decision "outrageous and unjustifiable" and vowed to consider legal action against anyone who had lied about her. She said she had refuted all the allegations against her, insisting there was "only one reason for not endorsing me - that I am a socialist".
The veto on Ms Davies is the first move by Labour HQ to interfere with a selection since Sharon Atkin was blocked in 1987 for calling Neil Kinnock a racist. It followed an early morning four-to-one vote recommendation against her standing as a Labour candidate by the disputes committee in the wake of a four-hour hearing on Monday.
Mr Blunkett, shadow Education Secretary, and Ms Lestor, the overseas development spokeswoman, voted against the recommendation when it came before the full National Executive Committee yesterday afternoon, while Mrs Beckett, shadow Health Secretary, abstained.
Dennis Skinner, the left-wing MP for Bolsover, who dissented on both votes, called yesterday's events a "defining moment" for the Labour Party and the Labour leader. A person who would have been a first-class MP, a party member since the age of 16, had been dismissed purely because she was of the left, he said.
Nigel Harris, the committee's chairman, said: "We had many troubles in the Eighties with Militant. I don't see why we should have cancers eating away at the inside of us. You either join the Labour Party and support the Labour Party or stay out."
Tom Sawyer, the party's general secretary, said the NEC had found "fairly conclusively" that Ms Davies was not a suitable Labour candidate because of the "numerous occasions" she had defied the Labour whip as an Islington councillor.
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