If you're a big fan of Katherine Jenkins then you'll definitely love tonight's episode of Britain's Secret Treasures. Wrapping up the series in style, the Welsh songbird travels to Boverton in the Vale of Glamorgan to tell the story of a remarkable find of Iron Age jewellery. Meanwhile Bettany Hughes visits the Isle of Wight to meet the girl who uncovered a 5,000-year-old tool while on a school trip, and Mary-Ann Ochota dives for treasure at the site of the sunken HMS Colossus off the Isles of Scilly.