Masonbrook was originally the seat of the Mason family but was later bought by the Smyth estate. At the time of Griffith's Valuation it was occupied by James Smyth and was valued at £60. It is recorded in the Valuation and the 1906 report on Untenanted Demesnes as located in the townland of Moanmore East but is shown in the townland of Masonbrook on the 1st edition OS Map of 1842. In 1906 it was valued at £60. It is not shown on the 25-inch edition Ordnance Survey map and is no longer extant.