So I killed Opera from W7TM and relaunched. Both WTM and O-TM reported similar as before.
I killed opera again and renamed both the profile and cache folders (opera://about). Deleted the install folder and installed a new O-60. I renamed the new profile and cache folders and renamed the old back. Relaunched Opera and have all my windows back so all good.
Happy to report that even though W7TM reports fluctuating RAM usage most actually go up and reset at alower value and then tick up again. End result is a reasonably stable 11GB of RAM in total use. So looks like the reinstall cleaned up whatever was happening and now my opera seems "stable".
Thank you for your help