In 1765 St James Theatre was granted a Royal Patent, making it the first provincial Theatre Royal in not only Bath but England. There were many plays that took place in this building, such as "King Richard the III", "Macbeth", and "The Grecian Daughter". The theatre became so popular that the tickets were selling out every night and therefore more space was needed. At this time, in 1805, a new building was put up.

This building has a direct correlation with one of Jane Austen's popular books, Northanger Abbey. "Austen scholars are generally of the opinion that [a] scene takes place in [Northanger Abbey] that takes place in [the Theater Royal in Bath]. This is because "Jane Austen visited Bath several times in the late 18th Century...  She was a regular visitor to the Theatre Royal in Orchard Street during the last five years of its existence". It is believed that she "used the interior as a backdrop in her novel Northanger Abbey".

The citation from Northanger Abbey:

At the beginning of the fifth, however, the sudden view of Mr Henry Tilney and his father, joining a party in the opposite box, recalled her to anxiety and distress. The stage could no longer excite genuine merriment — no longer keep her whole attention. Every other look upon an average was directed towards the opposite box; and, for the space of two entire scenes, did she thus watch Henry Tilney, without being once able to catch his eye... 

suggests a setting that directly reflects that of the Theatre Royal in Bath. Scholars argue that "The side boxes at the lower level each side of the Theatre had seats (the upper two levels were standing galleries), and Austen scholars are generally of the opinion that this scene takes place in them, probably because Miss Austen’s actual situation in society would most likely place her attendance there.  However, at the time the book was written, the Theatre also had grand boxes at the upper rear, arranged in a semi-circle with the two extreme boxes also facing each other.  The social (and financial) status of the fictitious Allens and Tilneys would have made these boxes more likely of their patronage". 

Citations: 

“Theatre Royal 1750 - 1805.” Old Theatre Royal Tours & Masonic Museum, oldtheatreroyal.com/museum/theatre-royal-1750-1805/