Sebastian is a non-canonical character who was created for the adaptation of The Manhood of Edward Robinson, the tenth episode of the Thames Television series The Agatha Christie Hour. Like Poppy, Guy, Jeremy and Diana, Sebastian is also a friend of Lady Noreen Elliot and part of the "burglary for fun" scheme that Noreen had started. It is Noreen's and Jimmy's turn to conduct a burglary in order to win a bet for the prize money. But unlike Poppy, Jeremy and Guy, Sebastian did not go to the Tantalus Hotel to try to frustrate Lady Noreen to prevent her from winning the bet.
Sebastian only turns up later at the Cafe Paris where Lady Noreen must wear the stolen necklace for a certain amount of time in order to be declared the winner. There, Sebastian tries to dance with Lady Noreen. For a while Lady Noreen evaded him but he gets a chance. During the dance, he constantly tries to place his hands around her neck to take the necklace off. However Lady Noreen runs off. Sebastian and his friends give chase but are blocked by Edward Robinson. Noreen manages to keep the necklace on until the clock chimes, at which time Sebastian congratulates her on a well-deserved victory.
This character does not exist in the original story.
The part of Sebastian is played by Simon Green.