I guess it's early days but I tried this half hour ago and so far, hey presto! This comes after a couple of days of leaving off for 24 hrs, then retrying - unsuccessfully. Also changed all the ECO and Anynet parameters that other folk have recommended, and did a couple of factory resets - all to no avail.
However, switching off the power off and back on again, (with batteries out of the remote) and then switching on with the tv on/off button, then putting new batteries (and they weren't old ones before) it seems to have solved the problem.
Now, I can't guarantee that this final solution was the one that did the trick, given every previous attempt at trying to correct the fault; however, it was after this last 'simple' restart and new batteries that the tv seems back to normal. It's worth pointing out that this is the first time the tv has gone awol in 4 or so years even though there have needed to be battery changes in the past. The 'possibly faulty' batteries were Maplin Extra Long Life(!) - these have been replaced with 2 x IKEA AAA's.
As with all techy stuff, it's worth being patient, go back to the beginning and start from scratch. More often than not, a solution is close at hand and quite simple, especially when 'updates' are automatically applied. Not so with my Packard Bell Netbook, however, the BSOD after an update in November 16 left me with an useable PC. Downloading an ISO from Microsoft, I was eventually able to install a new Win 10 OS (rather than the Win 7 upgrade to Win 10 which I was running), whilst keeping access to all my files - unfortunately the apps were lost. Once I find the license key I should be able to reinstall MS Office 2010!!