Well, it's died again and I've rung TS.
Of course, following NTL's advise whilst on hold, I rebooted the cable modem and of course it was working again.
After speaking to the TS chap, he ran some diagnostics and could only report it was running fine. I did mention the firmware change and he dismissed that (or didn't understand what I was on about).
The only thing the chap could suggest is to call them back once my connection has died because he can then formulate a report to pass on to an engineer.
Oh well, things never get sorted first time round. LOL
I probably only have to wait 30 mins or so before it dies again