[ALUG] Debian GB Localisation

Here's a new one, I haven't yet entirely figured out with Google ... What places do I need to modify to rid myself of all the US-isms? I've changed the Region and Keyboard layout to British in KDE, and I also worked out that I needed to add a specific GB localisation package for Iceweasel. What other places exist for setting the localisation? Are there any other applications which require additional GB localisation packages? I installed the localization-config tool after reading about it online, but if I run "update-locale-config -l" there doesn't seem to be a mention of GB English ... Thanks for any pointers, Peter.