"Oh, yes, I knew Salk," Helen said, nodding quickly.

"He was a friend of my father's. Mine too, for that matter, but at the time I was fighting to be allowed to sit for a degree at Oxford so I was a bit preoccupied with other things. Salk, Watson and Crick, the Curies. I knew all of them and worked with them to some extent. Given the nature of my longevity, I didn't want to have my name on many things. Too many questions."