Well at least I know now I was not attempting something stupid. It is supposed to be able to mount .iso files.
Will try Thunar, as you suggest.
I think , now I have seen your result, there must be something missing on both my Debian systems, one witth Xfce, one with Gnome.
pcmafm-qt ?? That is Qt? Gnome and Xfce are not Qt
Thanks Rosika, I should be able to sort it now
Regards
Neville