Thanks but that ^ is exactly where I went looking for it and Opera is showing I have no extensions, add-ons or whatever.
I haven’t added any others myself

Surely Avast itself should be showing Opera on the Settings > Browser Integration page I mentioned if they were recognising one another. which clearly they’re not?

I’ve just downloaded WOT, Opera’s own version of WebRep to see if that works OK. It does but I still would very much like to know why Avast isn’t integrating with Opera as it is supposed to.