Passenger 4 (The Man from MI.5)

A passenger donning clear glasses was aboard the Fireflash flight in 1965 which took Lady Penelope Creighton-Ward from England to Nice so that she could meet with MI5 agent Jimmy Bondson. Towards the end of the journey, he was sat in the cocktail lounge. (TV: The Man from MI.5)

Other sources dated the activities of International Rescue to the 1990s, (PROSE: The Dying Days) the 2060s, (PROSE: Titan Declares War! et al.) and the 2080s. (PROSE: Captain Scarlet in Death Crash! et al.)

Behind the scenes
The puppet which "played" the passenger was also seen in several other episodes of Thunderbirds. It had speaking roles as Lord Silton in Vault of Death where he was voiced by Peter Dyneley and as Percy in The Duchess Assignment where he was voiced by David Graham. The puppet appeared in a silent capacity as a journalist in The Mighty Atom, at the launching of Ocean Pioneer II in Danger at Ocean Deep, and as a gambler in The Duchess Assignment.