Locale guru required - bash incorrectly displaying umlauts & acute accents after package update

Late last night I did a package update on my servers.

Now when I shell into any server there's some sort of character encoding problem which is displaying umlauts and acute accents for all special characters. So the "pipe symbol" becomes "lowercase o umlaut" and the "at symbol" becomes "uppercase E acute accent".

I've removed LANG, LC_ALL, LC_COLLATE and tried setting these to different values with no effect.

I've tried 'stty sane' and 'stty -istrip' with no effect.

Even 'export LANG=C LC_ALL=C LC_COLLATE=C' produces no effect.

If you're a locale guru, let me know what you'd try next to fix this.

Thanks.

My version of bash and locales available are...

rootÉhive1:ü# bash --version
GNU bash, version 4.0.33(1)-release (i486-pc-linux-gnu)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>

This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

rootÉhive1:ü# locale -a
C
POSIX
en_US.utf8