Many thanks. I did try the reset password approach, it said “confirmation sent”, but none received here.
Anyway, what I did was to remove and re-install our two main accounts on the three computers in this house. A bit of a faff because inevitably I got the odd password wrong but at least we were up and running albeit with a hiccup as I speak..
Then, after doing this, and almost by chance, I looked at the SMTP settings. I didn’t think I needed to but just decided to check the default and found the username was xxx@virginmedia.com! So perhaps, from what you say, after being dormant for a long time, it was activated/addressed before being deleted.
Does that make sense?
Well it’s sorted, so thanks again..