Government Conduct by allowing personal interests to sway their votes on traffic issues.
But the ombudsman, Edward Osmotherly, declined to name the four.
The council's Labour group claims the findings are 'another example of Tory sleaze' and is urging the council to name the councillors involved.
complaints by six residents about high-ways, in particular that some councillors who attended committee meetings in
the late 1990s had failed to declare an
The residents complained the Tories' decision to remove the red route designation from Belgrave Road, increasing traffic on Vauxhall Bridge Road, would benefit the four members who lived in the area by cutting traffic levels near their homes.
The ombudsman found three of the four had failed to declare a personal or private non-pecuniary interest at the committee meetings on 30 June 1998 and 26 January 1999. But he said that the interests were not clear and substantial. The fourth had a 'clear substantial interest' which was not declared either at those two committee meetings or the council meeting in July 1999.
This councillor left the committee table during one meeting, but 'hovered' in the doorway. The ombudsman described this 'hovering' as unwise.
Mr Osmotherly concluded that while the behaviour of the four amounted to maladministration it did not cause the complainants any injustice, and said it would be unjust to name the councillors. He rejected the other allegations.
A statement by the council, said: 'We welcome this thorough investigation into the matter which has resulted in all complaints against the council - bar one - being rejected.'