Bernard I have had the 'Tower of Empire' plate a few times(http://img211.imageshack.us/img211/5108/plate2ct.jpg)
Opalescent and comes in a few different sizes - bad photo above of a large one I sold on eBay years ago.
I would love to see a pic of the 'Scottish Pavilion' plate - same style as above I assume.
'Tower of Empire' is most common; I know companies did other glass plates with different lettering and scenes, e.g. 'Garden Club' so I thought
All of the beakers and cups I have, Dominions Avenue, Garden Club, Scottish Pavilion, North Cascade, etc. show different pictures - perhaps the plates all show the tower but just change the wording.
I collect most Scottish Exhibition glass (also postcards, ceramics, booklets, coins) - mostly 1901, 1911 and 1938
As a Glaswegian it is my heritage and some pieces were passed down to me.
The rarest items show the Tower looming over local villages, they are harder to get and I have great conversations with a real collector about all the firms that made the items, many were not Scottish.