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Great Aunt Sylvia appears in the Thunderbirds Are Go! episode Designated Driver. She's Lady Penelope's great-aunt, and visits Creighton-Ward Manor to inform her great-niece (and namesake) about the T.E.A. Lady Sylvia and her husband are the 4th richest couple in Europe. She is quite demanding and brave, she is used to getting what she wants and acts the part.


  • She's the only other member of Lady Penelope's family to appear in a Thunderbirds series.