youngoldbloke
The older I get, the faster I used to be ...
If your 80 year old grannie wants to take up cycling I suggest you advise her and help her choose the right bike, and maybe point her in the direction of cycle training for those new to cycling.Again, highway code changes never had anything to do with EU.
Difference between assisted 20mph and leg power 20 mph is rider, latter has skill and fitness needed to control that bike at 20mph. 80 year old granny doing assisted 20 mph may be too weak to stop at reasonable distance. Of course same can be said about 15.5 mph but, risk of serious or fatal injury drops dramatically with speed reduction.