Kate Atkinson said this quote

The clock had been Sylvie's, and her mother's before that. It had gone to Ursula on Sylvie's death and Ursula had left it to Teddy, and so it had zigzagged its way down the family tree......The clock was a good one, made by Frodsham and worth quite a bit, but Teddy knew if he gave it to Viola she would sell it or misplace it or break it and it seemed important to him that it stayed in the family. An heirloom. ('Lovely word,' Bertie said.) He liked to think that the little golden key that wound it, a key that would almost certainly be lost by Viola, would continue to be turned by the hand of someone who was part of the family, part of his blood. The red thread.