Not the imperial. I think I better reveal this one!
It is the Junior Dining Hall at Gloddaeth Hall.
White Rabbit on this Forum attended the place when it was a Girls School.
The link to Clares is that WR's grandfather started the store as Clares.
It was a Girls School but then became a Boys as St David's College.
Nick Elphick and Viscout Chelsea are ex Pupils.
If you want more, Google is a good search engine!