John Rowland wrote:
I found a road today (Knapp Road E3) with a standard T-shaped "No
Through Road" sign, and underneath were the words "Except Access".
Every time I try to figure out what that might mean, my head turns
into a Moebius strip.

According to Streetmap, when going west along Knapp Road, just after the
railway bridge, the road becomes Cantrell Road, but there's a line
across the road suggesting some sort of access restriction. Similarly
at the other end of Cantrell Road, where it meets Bow Common Lane, there
is another line across it. So I assume that Cantrell Road is
effectively pedestrianised except for access, with either some sort of
restricted-access barrier at each end or just No Motor Vehicles signs
with "except for access" plates.

If so, the No Through Road Except for Access sign is reasonably logical,
except that the only qualifying plate allowed on a No Through Road sign
is "except cycles". So it's either an unlawful sign or has special
permission from the DfT.
--
Richard J.
(to e-mail me, swap uk and yon in address)