Royal House, Machynlleth. This is a copy of a postcard by W.H.S. & S. LTD, London 16763-38. Royal House is a medieval building situated in Penrallt street, Machynlleth. It is said that David Gam was imprisoned here in 1404- 12, for attempting to assassinate Owain Glyndwr. King Charles I is supposed to have slept here on his way to Chester.