I ended up deploying IE10 with WSUS and everything's working perfectly now. There were a few LA websites in Birmingham which only worked with IE8 and Adobe Reader 9, but conveniently these have been addressed, so all users are now using IE10 and Adobe Reader 11.
I forgot to say, in my testing the problem is there with IE8 and IE9, on any supporting OS. The only solution is IE10, Firefox or Chrome.
It's unclear why Microsoft are taking so long to address the issue with IE9. You'd think they could take snippets of code from IE10, as the issue doesn't exist when this is installed.
We are virtualising our servers over the Summer break. Alongside this work we are also creating a new domain, migrating our staff and students to the new domain and rebuilding all of our workstations and laptops. The rebuilt workstations will have IE10. I guess we will have some website validations to do over the Summer too.
For information: I have received an update on this and another issue today. Paraphrasing the E-Mail I that came through today:
On the printing of blank pages: This will be fixed in a Microsoft update in the next 2 months. In the meantime the only recommendation is to use an alternative browser such as FireFox or Google Chrome or use the local outlook client. [So advice unchanged here]
On stripping out of original senders' E-Mail addresses in forwarded E-Mails: There will be a fix for this but Microsoft are unable to provide a time/date for this.