St Mellons Hotel was previously named Llwynarthen. The house was built in 1878 and was home to Sir Henry Webb, a baronet and commander of the Gloucester, Worcester and Liverpool regiments during the Great War. He also carried out duties as the member of parliament for the Forest of Dean, and later as the member of parliament for Cardiff East.
In its distinguished history, the hotel became the home of a Junior Lord of the Treasury, then was converted into a First World War military hospital. It was then transformed into the swish Blue Horizon Club in the 1920's, a base for anti-aircraft guns during World War II, before finally becoming a Hotel and Country Club in the 1950's