Usual Problem
There are an awful lot of apps out there that will only run on IE6. One of our suppliers is a major corporate and their helpdesk app runs only on IE6. Anybody who uses that app has to use IE6. Here in IT we have no influence over the supplier. Senior management have no real leverage because we are tied into a term contract and this in no way consitutes a breach. Worse still the helpdesk app was developed by another large company which puts the whole thing at one remove. So some of our users are stuck using IE6 until our suppliers change the helpdesk app or the contract ends.
I suspect that UK.gov are in the same boat. They can't start throwing their weight around with suppliers because no doubt that would contravene EU procurement laws.
The particular vuln that upset Google is stymied by our IPS so we're protected, but the worry is that sooner or later something will come along that the IPS can't cope with. It's also a pain supporting a handful of IE6 installs, not to mention dealing with all the shit that won't run on IE6 and making sure group policies and the like don't break IE6. Not forgetting making sure some idiot on the helpdesk doesn't "helpfully" upgrade the EU to IE8.
Developers royally screwed their customers when they fell for MS's spin on broswer tech. MS made IE6 as non-standard as possible to try to tie developers and their customers into IE and also kill off the competion. The thinking presumably being that if they could get enough of the interwebs to be IE compatible only then the rest would surely follow. Then MS changed their minds (presumably at the thought of anti-trust action) and left those developers and their customers out in the cold come IE7.