"Great Aunt Sylvia" is a Stub.
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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.


  • She's the only other member of Lady Penelope's family to appear in a Thunderbirds series.
  • Sylvia Anderson passed away in 2016.