Jim is a character from Edge Of Impact.
One day, while working at the top of the British Telecom Tower with his colleague Stan, an aircraft hits the tower, consequently putting the lift out of action and trapping the two gentlemen at the top.
Thunderbirds 1 & 2 arrive at the danger zone. Alan operates the Booster Mortar, a tracked vehicle with a mounted mortar cannon, which fires two low-altitude escape harnesses through the window of the relay tower's control cabin. Donning the escape harnesses, Jim and Stan climb on to the balcony, activate their jetpacks and fly clear as the relay tower finally gives way, crashing to the ground.