Source: A Tale of Time City (1987), pp. 78-79.
Quotes from book
A Tale of Time City

A Tale of Time City was first published in 1987 by British author Diana Wynne Jones. It tells the story of a girl, Vivian Smith, who is kidnapped while being evacuated from London during World War II and caught up in a struggle to preserve history. In this novel, Jones explains time travel with more reference to our current understanding of science than she does in many of her other works.
Source: A Tale of Time City (1987), p. 45.
Source: A Tale of Time City (1987), p. 87.
Source: A Tale of Time City (1987), p. 73.
Source: A Tale of Time City (1987), p. 21.