Thanks but unfortunately it did not work.
I also tried with a space between the W and the rest of the code as, for some reason, when I copied and pasted it the space, if there is meant to be one, was not included. Still the same negative result
Literally just 10 minutes to go now before the current licence expires. What's going to happen then?

So far.......................................nothing.
I suspect the proof of the pudding will be on PC reboot but at least it appears I'm still protected during this session.
Of course, if everything goes OK and there's no problem AVAST will be my favourite people again.
If my experience here helps alleviate others concerned about this matter then I'll be even happier. But really this is the job AVAST should have been doing themselves - talking to their users, keeping them informed about what was going to happen on expiry, answering their, quite reasonable, questions and, of course, dealing with any problems.