The 20mph speed limit in Lewes is being ignored. Why? One reason is lack of enforcement. Why not call a three month amnesty? Use local press and posters to argue the merits of 20mph.
Weakest pedestrians, indeed all pedestrians, narrow pavements, cyclists, other vehicles, all would gain.
In fact 20mph is 16 to 18mph. Always drive a margin beneath the limit to guarantee the speed is never breached. The same that applies to 30, 40, etc.
Lewes, the medieval town that must have suffered donkey cart traffic jams 300 years ago, would gain hugely from 20mph being observed.
At the end of the amnesty, transgressors would face prosecution, £150+. Make the enforcement self-financing. Those who can’t obey a wise law can help pay for it.
A second and effective alternative is the road engineering in suburban London - speed bumps. Speed bumps both in height and frequency that guarantees 20mph.
Slow Lewes down. Make it a pleasant town where the car does not rule.