Steven:
Thank you so much for checking on this for me.
I did follow your suggestion to trash the Cache for Safari on my iPad but unfortunately doing that hasn't removed iOS's insertion of an X in place of my Back/Home button.
Are there any other Caches which I should clear?
I see that there is an iOS update (how I hate iOS!) to iPad 14.06 available and I am about to install it to see if it helps.
If that fails, would changing the Config HTML for the Galleries to:
Position back button at "Top", "margin-left=40px" do anything useful such as providing a new placement position for the back button which is clear of Apple's X icon?