Why does it have to be female?
It could be men too. If it doesn't accepts ils, report it.
Why do we not need 'pas' after savait here?
It was replaced by "personne". Negation in French is composed of "ne" and an adverb/adjective (pas, plus, jamais, rien, personne, aucun(e)).
"personne" and "rien" can also be pronouns and act as subjects so they are at the beginning like in this sentence.
Thank you. I didn't realise the complement to 'ne' in a negation could actually precede it, I can see that one is probably going to catch me out a few times yet!
Why can't it be ils????
Why couldn't you use "n'a pas su" here?