As I checked the steps again, I discovered the skin file had been overwritten. I'm working in a docker container and failed to modify both files in the mount, thus one overwrote the other. But even after correcting that , the tour.xml did not include the added line: <layer name="logo" type="image" keep="true" url="skin/English_Optics_Logo-transp.png" x="20" y="20" height="30" width="prop" /> after creating a vtour.
I have attached the skin & xml files to see if I have entered the code correctly. I have changed the extensions to txt so they will be accepted.