A homing device disguised as a St Christopher brooch was given to Duchess of Royston by Lady Penelope, before see sets off to America for a meeting with Wilbur Dandridge in The Duchess Assignment
The Duchess was tracked on her travels by a monitor inside FAB 1, and after she was kidnapped by Chandler and Brophy, Scott was able to find her using a tracking device on board Thunderbird 1.
The Tracking DevicesEdit
The homing device has a massive range, Lady Penelope was able to watch the Duchess's movements from her car and home in England, while she was as far away as New York in America.
Thunderbirds 1 & 5 were also able to pin-point her location after she was kidnapped, which gave International Rescue the information to make a rescue and save her life.
John tracking the Duchess in Thunderbird 5
The tracking device on board TB1