| "Great Aunt Sylvia" is a Stub.|
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- She is based on and voiced by the late Sylvia Anderson, the voice of Lady Penelope Creighton-Ward in the original Thunderbirds series.
- The dress she wears is based on Lady Penelope's outfit from the classic episode The Duchess Assignment.
- She is the only other member of Lady Penelope's family to be seen in a Thunderbirds series.