Siwan, the last Queen of Wales [audio 8min]

When, twenty years ago, Catherine Gibson bought Garth Celyn, an old house on the North Wales coast, she had no idea that it had blue blood. Local folklore claimed that her new home had been the dwelling place of the Welsh Royal family until the 13th century and that it was where the last queen of Wales - Siwan (Joan) - died in 1237. For many years Catherine Gibson fought to establish the truth. Now the house is visited by historians and school trips. Journalist Stuart Robinson has been to Garth Celyn to meet Catherine and to hear some of the play Siwan, by Saunders Lewis.