Once again thank you for the suggestions.
I downloaded Malwarebytes and ran the scan, which showed no problems.
I then looked at the link to the Youtube video. "Google Settings/Advanced/Restore settings to their original defaults" seems to have solved the problem - 24 hours without adverts popping up.
In fairness to Free Live Radio it clearly wasn't as bad as some I read about in the above links. It hadn't taken over my browser - just giving me some unwanted and irrelevant adverts.
Incidentally, my internet was working at snail's pace with Malwarebytes installed - I have uninstalled it and am back to my previous speeds. I am using Avast which has always done its job for me.
Thanks again.