She was also the daughter-in-law of Jeff's mother and father.
The official cause of her death is unknown, due to conflicting sources - such as illness, a road accident; and the most official death so far, avalanche (The Complete Thunderbirds Story).
Howsoever it occurred, her sudden and unexpected passing was the tragedy of her young family's lives - and would inspire her widower, Jeff, to create International Rescue - to save other people's lives, around the world - in her memory.
- Lucille was never officially named, or referred to, on-screen. While the TV21 magazine briefly mentioned a "Mrs Tracy," it wouldn't be until the early 1990s when Alan Fennell named and incorporated her into the Thunderbirds The Comic storyline The Complete Thunderbirds Story.
- Whether she's considered canon to the original television series, or not, is debatable - as neither Gerry nor Sylvia Anderson were involved with TCTS. The comic also altered numerous established story elements (eg, its setting being 2026, rather than 2065). However, later publications have retroactively included her in the 2065 timeline.
- In Joan Marie Verba's Countdown To Action!, Lucy's maiden name was Taylor.
- Some sources differ over the order of birth of Lucille's sons. Some says the order was Scott, Virgil, John, Gordon and Alan, which accurately reflects their assigned Thunderbirds (when Alan's in Thunderbird 5). However, other sources say that John was the second son and Virgil was the third (probably reflected in the character introductory part of the opening credits).