Go to the web page. Once the page is loading, mouse to the address bar and Left-click the icon. Select Permissions. In the menu, Make sure the ones you want to use are set to Ask or Allow.

I can't tell you exactly what went wrong, but I have a touch screen which I do not use but I had accidentally swiped it and lost my open programs, I thought they'd all closed down but when I reopened one program (a downloader) from the taskbar icon Firefox opened - with a different session ??? - and behaved as in my OP.

Anyway, eventually other anomalies came to my attention so I rebooted and am back to normal. (I wonder if it was to do with Tab Session Manager which I recently installed as I was having a problem with restoring sessions. I wish FF would bring back the old History interface/performance.)

However, your kind response was not in vain, Fred, as it's about time I checked what the squiggles (poor eyesight) on the left of the site name are about!

Thank you very much.

So, is the problem settled? If it is,

Please flag your last post as Solved Problem so others will know.

I didn't feel that I should mark it a Solved, as it was an anomaly rather than a method of solving the problem I described. I've done it now, thank you for the advice :)