As you can see from the attached data from the Representations book at Kew, this was Registered as Class 1 (metal), so assume the first picture below (which would have accompied the original 1908 request) is showing the metal part of the Registration only, and not the glass liner - there wasn't any caption with the picture. Prototypes - made initially to simply represent the shape or design of a finished article, were often made of a material other than that which the retailed piece would be constructed from, and in this instance we may be looking at a base metal representing the EPNS frame.
It's possible that your glass liner may well have fitted into/onto this EPNS base. Looks as though it might be possibly some sort of sauce/salt/condiment/jam container for the table - I'd have thought unlikely to be for soap.
In order to clarify this, you will need to post a picture - even if not of high quality - interesting to see that not all three sections of the container are identical in design, which may confirm the idea of this being for condiments - but not sure - what do others think.
The other picture is from the Register and shows details of the Registrant i.e. the name to whom 533829 was allocated - trust details are legible, but if unclear it reads.............'The firm trading as W. J. Anthony, 7 Unett Street, St. Georges, Birmingham. Stampers and Pierces.', so they bought the glass from elswhere, which was quite common I think.
Date of Registration was 5th December 1908, and doesn't appear to have been extended.
So - Waiting for your picture.
