The classical guitarist is named Liona Boyd (not Christina). She recently wrote her autobiography called In My Own Key: My Life In Love And Music. In it she talks about touring with Lightfoot, and also about her affair with Pierre Trudeau.
I only read the Lightfoot references ...
If you are interested in learning more about her, she has a web site here:
www.lionaboyd.com .
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Valerie Magee