Thank you silverfox.
You have been helpful and generous with your time, as on previous occasions for me.
As I understand it, the two options you suggest would require the url to be recorded at the time of viewing the Ancestry Member Tree.
I find on many occasions that I "surf" many Member Trees and it is often the case that I realise sometime (days) later that I require to go back and revisit that tree. This often occurs well before I realise that I wish to record information from that tree.
So having seen the tree previously the only way I can find that tree again is to re-undertake the original search process that led to that particular tree being found. This is very tedious.
Often I have noted the tree owners name after printing a page of their tree, or I have corresponded with them via a message.
I am surprised Ancestry does not have a "search by tree owner's name" function.
Perhaps there are privacy reasons?