But P1971, the problem as you point out is parking (permitted on Sundays and illegally done the rest of the week) blocking traffic flow.

Road width is irrelevant if there is the same yellow line arrangement and lack of adequate enforcement.

Double yellows all along the road (with the exception of proper parking bays of course) together with adequate enforcement is the only solution to this issue. With this, there would be none of the current traffic flow problems, either with the current road layout or a narrowed solution. Seeing as the narrowed solution provides improvements for pedestrians, I'm all in favour.