Plot: Penelope concludes her journey with a trip to the Queen's royal residences in Wales and exploring the regal links, including ceremonial investitures, Pembrokeshire corgis and the Royal harpist. She pays a visit to Caernarfon Castle, where Prince Charles was invested as Prince of Wales in 1969, and the Royal Mint, as well as Aberfan in the valleys of south-west Wales, which was the site of a disastrous coal mining accident in 1966