Explore the Unseen Thunderbirds in the latest part of our behind the scenes journey through the creation of Gerry and Sylvia Anderson's timeless television series. This time, we take an in-depth look at the making of one of Penelope and Parker's finest hours, "Vault of Death". With the help of newly treasures from the archives, we uncover the challenges faced when this half hour episode had to be expanded to twice the length. https://www.youtube.com/watch?v=7-ADln6p3Es