A cycling campaigner has blamed CS11’s legal defeat on Transport for London’s “watering down” of the project – and said it is time for London mayor Sadiq Khan to “improve his politics game”.

Justin McKie of the Regent’s Park Cyclists group told the Ham&High: “The key question is what happens next.

“CS11’s not over – now I’d like to see TfL step up and Sadiq Khan improve his politics game.”

Sir Ross Cranston found in favour of Westminster Council in the High Court, ruling that TfL had failed to adequately consult it over the plans and did not plan for Westminster’s refusal to consent – save by internally proposing a piecemeal version of the scheme omitting the contested Westminster Streets.

Justin added: “They watered down the plan in order to try to please everybody and ended up in a state where they’re pleasing nobody. There was a good plan that had 60 per cent public support, but the decision to do it piecemeal has backfired.

“It’s clear that if they had been more assertive then we would have had a different outcome.”

A TfL spokesperson said: “We are disappointed with the ruling, which focuses on procedure rather than the merits of the scheme.

“This junction in Swiss Cottage is one of London’s most dangerous. The scheme that was the subject of this ruling would help to protect all road users and particularly those walking and cycling, while significantly improving the area for residents, visitors and businesses.

“We will take the judge’s findings into account and are also urgently exploring all the options available to us to reduce danger around the Swiss Cottage gyratory, which includes considering appealing the decision.”

Campaigner Jessica Learmond-Criqui, who led neighbours’ opposition but withdrew her legal challenge when Westminster formally submitted its own, said after the ruling: “This is not and never has been a challenge to the principle of cycleways or safe cycling. It was always a challenge to the unacceptable and high-handed manner in which TfL makes and implements its decisions. The High Court agreed with us.”

The mayor’s walking and cycling commissioner Will Norman said: “Cycle Superhighway 11 will play a crucial role in making the area safer for cyclists and pedestrians, removing the outdated, dangerous, and traffic-dominated gyratory at Swiss Cottage.”

TfL is considering appealing the judgement.