Big House was originally built in 1750 and owned by the Owens of Orielton who were the Landshipping Coal Agents. The house was constructed using stone and roof materials from an older, ruined mansion further inland. The house's original, simple, rectangular design has undergone several upgrading alterations. The final occurring in 1830 when a third storey was added to the western wing, and the entrance was moved to the North facade between two bow-fronted full height extensions. There is a service court with stables and servants quarters to the rear. These alterations were instigated to mirror the larger Picton Castle on the opposite side of the river (the North Facade overlooks the river Cleddau and a quay).

The house was originally owned by Sir John Owen, later passing to his son Hugh. Hugh Owen married Angelina and had 3 children - William, Angelina and Frances, When Angelina died, he married Hentietta and had two more children - Augustus and George. Due to poor estate management and political misadventure, High Owen lost his fortune in 1856. The estate was placed for sale in 1857 and described as 'Beautifully situated on the banks of the River Cleddy and opposite Picton Castle containing - sunday Bed Rooms, Hall, Parlour, Dining Room, Drawing Room, Nursery, Library, Servants Offices, Range of Stabling, Coach House, Saddle Room & Granary Over Yard, External Walled Garden, Orchards, Wood etc, nearly 6 acres in all'. The property was bought by William Owen, a self made businessman and architect, who became one of the richest landowners in Pembrokeshire. However, by 1890 the Big House had become a ruin. In 1922, the Landshipping Estate, including Big House, was sold at auction. The associated cottages continued to be lived in until the 1970s. In 2011, Big House featured on episode six of the BBC television series Restoration Home.

Maritime Officer, RCAHMW, March 2012.