Opponents of the Solicitors Indemnity Fund (SIF) are furious that four directors of the mutual fund were allowed crucial votes that ensured the monopoly's survival.
Four council members from firms on the SIF panel stayed away from the meeting after advice from counsel.
But all four SIF directors - chairman Peter Williamson, George Staple, Angus Andrew and Paul Venton - were allowed to vote. All voted to retain SIF.
The managing partner of one major City firm says: "It's a fundamental rule that you never vote on something in which you have an interest. I suppose they would say they don't have a financial interest, but that is not the only kind of interest."
November Meeting Group chairman Christopher Hales says the SIF directors had a vested interest and should have done "the honourable thing".
"It would have been better if they abstained, and the fact that they didn't made all the difference, didn't it?"
The City of London Law Society (CLLS), which vehemently urged the council to scrap SIF, also suffered a blow when only one of its five representatives voted to discard the mutual.
Staple voted for SIF while Lesley McDonagh, David McIntosh and Fiona Woolf of Cameron McKenna stayed away due to pecuniary interests. Only Law Society president Michael Mathews voted to scrap SIF.
CLLS chairman Tony Sacker says Staple is a member of the CLLS committee which recommended SIF's abolition and says Staple did not seem to dissent then.
"I don't know what's happened in the interim to change his view," adds Sacker.
Staple says he did not commit himself either way to the CLLS and adds: "I do not accept that I should not have voted. I was put on the SIF board by the council and I had a responsibility to express my view."