Councillor Brian Coleman cut a ribbon at 8am on Friday morning to re-open Partingdale Lane sparking outrage among residents and opposition councillors who were not told about the ceremony.
Mr Coleman was joined by council leader Victor Lyon, Totteridge ward councillor Kevin Edson, and members of the Woodside Park Garden Suburb Residents' Association (WPGSRA), to celebrate their victory after campaigning five-and-a-half years to get the narrow road with no pavement re-opened.
Mr Coleman said: "I'm delighted. Democracy has prevailed. A right has been wronged." But Partingdale Lane resident Mel Simpson said the ceremony was 'distasteful'.
"They just went and signed the order without a debate. That's not democracy, that's a dictatorship, that's steaming in and taking over."
Liberal Democrat Wayne Casey, the ward councillor for Partingdale Lane, was also not informed about the ceremony. He said: "It's one thing to pursue an issue which they say is a manifesto commitment, it's another thing to rub the residents' noses in it in such a triumphalist way. I look forward to the day we kick them out of office, nothing has made me more determined than this act of triumphalism."
The road was closed in March 1997 by the previous Labour/Lib Dem administration because it was feared that pedestrians, cyclists or horse riders would be involved in a serious accident with speeding drivers on the lane's blind bends.
Less than a week after regaining control of the council in the May elections, the new Conservative administration announced their intention to re-open the lane, which was used a short-cut between Woodside Park and Mill Hill.
Residents believe Mr Coleman acted unlawfully in late August when he signed an executive order to re-open the lane, by-passing the committee system. They are taking Barnet Council to the High Court in a bid to reverse the decision. The council argues it was a perfectly lawful decision.
Mr Casey added: "I hope Coleman has a particularly miserable Christmas. I think they're going to have blood on their hands and when that happens I'm going to pursue them out of office."
Robert Shutler, chairman of the WPGSRA, was one of the first to drive down the lane soon after the ceremony. He said: "The council has done a good job and providing people drive safely and the residents don't put obstacles purposely in the way I'm sure we can all live happily together."
The road is now a 20mph zone and there is a lane-narrowing in the fastest part of the road to slow traffic.