Campaigners posted a video online which says: “Slow speeds are the single most effective way of reducing road casualties.”
Camden, the City, Lambeth, Southwark, Lewisham and Hackney are among councils that have or plan 20mph limits, it adds, but “in Westminster just one road has a 20mph limit”.
Ed Argar, Westminster cabinet member for transport, said the council kept the effectiveness of 20mph limits under review but added: “The average speed here is lower than that.”