The glass outside the case

The object was to be photographed through the display case because it could not be moved that day. Every change in my position brought another ceiling light into reflection on the glass. Moving closer made the object's far edge difficult to keep in focus. A printed information panel blocked the lower section, and opening the case was not permitted while visitors were present. Whenever the corridor filled, people passed between me and the object. The photographs had to show the whole piece clearly, not simply enough of it for somebody to recognise.

Describe the difficulties of photographing the whole object clearly. You may support your points with brief quotations.