On Friday afternoon I went to the Alliance and Leicester home page, intending to read my online statement like their nagging email had told me to, and was surprised when I got a popup saying "Please be aware that your browser is not supported, therefore this site may not work correctly." Huh? It's Firefox, which I've used happily with A&L internet banking for over a year... ah, but it's Firefox on Linux, which I haven't tried before. And the popup was quite correct about one thing: the front page was sufficiently mangled that I couldn't actually get to the login link.
Over the weekend, using Firefox on a Mac, I navigated (problem-free) to the login page and bookmarked it. Sure enough, if I go direct to that page (https://www.mybank.alliance-leicester.co.uk/index.asp) using Firefox on Linux, it a) doesn't show the popup, and b) works fine. (In fact, I can just turn off CSS on the home page and it works okay, but last thing on Friday afternoon I didn't think of that... duh.)
I am now wondering whether, if I tell them about this, they will stop my workaround working, too. :-/