Terry Harper wrote to uk.transport.london on Tue, 4 Jan 2005:

"Mrs Redboots" wrote in message
...

Not entirely, as I know Co. Derry had/has at least one code with a Z in
it, but I can't remember what it was, and Husband is now back at work.
S was mostly in Scotland, I do know. SI was, I think, somewhere in the
Republic and IZ was - sheesh, I'm thinking Derry City, BICBW!

Annabel, Londonderry had/had IW, UI and YZ. IZ is County Mayo. No SI
allocated AFAIA.

That's right, it was YZ I was trying to think of. I think they've
finished the *IWs now and are going through the *YZs? UI is Derry City,
isn't it, rather than Co Londonderry? I remembered this morning that IL
is Co Fermanagh
--
"Mrs Redboots"
http://www.amsmyth.demon.co.uk/
Website updated 2 January 2005