Don't believe it
About 2 hours after the outage began, @BTCare posted that "Engineers are now on site" (God knows where they had been, but that's another issue), and less than an hour later my Infinity connection is working like a charm again (so were those of other users).
So they determined that the router is faulty and repaired/replaced it within an hour? But it takes them two hours to even get on site? A company of that size doing manual fail-over? Hard to believe.
My money is on human error to do with the purchase of EE (and network changes related to that). But admitting failure is of course becoming increasingly politically incorrect. Attributing failure to others (kit and people) is the way to go.