Modern downward tinkering of speed limits is practically all about
anti-car, not common sense, cf ever increasing swathes of 20 mph
zones, etc.

Cite?

I was with you until that. Some 20mph zones are excessive (the
ludicrous one on the approach to Ambleside was one example but it's
now mostly been increased to 30, and most people did 30 anyway), but
many or most of the ones on estates are justified.

That said, the better approach on newer residential estates is to
design the road layout with curves and natural chicanes (on-street
parking) so the natural speed is 20mph or below, then it doesn't
matter if the limit is the default 30. This is done to great effect
on many Milton Keynes estates, especially newer ones.

Neil

Chris / Neil

I was specifically thinking about the London Borough of Merton which
for the last three years has been going through the borough converting
whole swathes of streets (not enclosed estates) into 20 mph zones
(from 10 to 20 roads at a time!). The SW19 and SW20 postcode areas.
Minutes of the Street Management Advisory Committee meetings can be
found he http://www.merton.gov.uk/council/com...tee&com_id=221

Ken