Many thanks for your help - I forgot to mention one thing that could be important - I'm not sure...when I carried out the Ford "dashboard test", I had an error in the dtc section - 262. A bit of research told me that it wasn't important and was a communication error of some sort.
Ford had to sell them and fit them at £99 tell ford to remember watchdog on the tv where the issue was high lighted it wont be £600 theyre taking the mick on that one i assure you have the fault diagnosed and if its the cluster tell them whats above
Well...a little more research and - like loads of other Focus owners it seems - removed the cluster and cleaned the PCB with WD40, left it to dry overnight and having put it in this morning, the dtc has cleared - it now says NONE.
One point to note is that fault kept coming up after the battery had been disconnected - it would never clear. So - has the magic WD40 fix found another successful end?
Time will tell I suppose and hopefully I won't find out waiting in a right filter lane like I did yesterday...