Somerset House is (or was) a substantial classical Georgian mansion designed by John Carr in the 1760s, and is grade II* listed. The house was owned by John Royds, a local merchant banker. Later the Rawson family established a bank on the premises, later to become the Union Bank. The name Somerset House was given to the property by a manager of the bank who had interests in that county.
The house once had extensive grounds stretching for some way to the south. These can be seen on the OS map from the 1850s, surrounded by the growing town centre. By the 1890s Rawson Street, Powell Street and Commercial Street had been laid out, with the infill becoming more dense over the next 50 years. The infill means it is not now possible to get far enough back to show the whole building in one photo, even with a reasonably wide angle lens - there is an east wing to match that on the west, although rebuilding means the wings are not symmetrically placed.
The west wing is obscured by a two storey building, and a row of free-standing shops built between the wings. All sides of the building including the long rear facade have had shop fronts inserted. Part of the rear can be seen on the right in a photo of George Street:
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The upper parts of the building have been unused for some time, but have retained high quality rococo plasterwork and chimney pieces.
After a long period of neglect and abuse Somerset House is now to be renovated / redeveloped.