In the latest episode of Thunderbirds Unseen, we take an in-depth look at how two episodes were expanded following the decision that each Thunderbirds episode would be an hour long. "Perils of Penelope" and "Terror in New York City" are two well-regarded episodes with action packed-plots & arresting visuals that continue to enthral after six decades, but what were their original storylines? With newly unearthed 35mm film and studio documentation, we explore these episodes with co-creator Sylvia Anderson and directors David Elliott, Des Saunders, and David Lane and challenge some "established" facts and showcase unseen footage. https://www.youtube.com/watch?v=5VchuN099cA