In message K7c7o.13937$Ai7.4940@hurricane, at 13:15:40 on Sat, 7 Aug
2010, Roy Badami remarked:
I know that Cambridge, where I live, was on the list - i.e. you've
always been able to write just "Cambridge" rather than "Cambridge,
Cambs." and I rarely-to-never see anyone include the "Cambs." in an
address here.

But I've always wondered what the general rule is as to when the county
is omitted. Is it basically County Towns (such as Cambridge, county
town of Cambridgeshire), plus those of the modern metropolitan counties
(e.g. Manchester as effectively the County Town of Greater Manchester),
plus of course London, which is a bit of a special case (in lots of ways).

Or is it more complicated or arbitrary than that?

It's very simple, there's a list of "Post Towns", and everyone should be
aware of the one where they live. A long time ago the Post Office sent
postcards to everyone telling them, and it's the bit in CAPITALS if you
get a PAF-derived letter. The county has been optional for a long time.

Where I live, "NOTTINGHAM, Nottinghamshire" would look a bit odd,
especially as Nottinghasm is a unitary authority, and in that sense is
not part of Nottinghamshire!
--
Roland Perry