Place of Origin:
The Eye of the Giant
Tilly was Nancy Norton’s maid. She went with Nancy on the expedition to the island of Salutua in 1934. Because the Third Doctor created a time bridge to the island from UNIT in the future, several potential timelines were created. (The Eye of the Giant)
She died with the expedition when the volcano on the island erupted after Brokk’s ship crashed into it.
ALTERNATE TIMELINE 1
She was one of the first people who Nancy implanted with Brokk’s eyebrain fragments, converting her into a minion. She helped Nancy take over the expedition’s crew after leaving the island, then aided in her campaign to control the world.
ALTERNATE TIMELINE 2
She was killed when the Third Doctor used his sonic screwdriver to shatter the eyebrain fragments.