It has been stated here many times that the postcode system was devised
purely for Post Office convenience, however, HA5 contains two roads
called Pinner Road at opposite edges, and I can not see why the PO would
have viewed that as convenient when they only had to move one of the
boundaries by 100 yards to put the Pinner Road which straddles the
Northwood boundary entirely into Northwood where it belongs IMO.

While I'm here, the LCC renaming of the 19020s-30s seems to have missed
the fact that there were two Brook Streets in London W. Now that one is
in W1 and the other is in W2, it's not a problem, however, is this the
only case of two roads of the same name in the same 1930s postcode which
the LCC failed to deal with, and if so, I wonder why? Perhaps both had
someone influential living there and they didn't want to upset them.