Complex sentence: The identity of the architect is not known, although the design is reminiscent of the work of William Kent although modern research tends to suggest Thomas Paty was the architect, and it is also not known exactly when the house was built.
Split into simpler sentences: The identity of the architect is not known, and although the design is reminiscent of the work of William Kent modern research tends to suggest Thomas Paty was the architect. It is also not known exactly when the house was built.