Citizenship Referee no passport?

We have someone in mind for the referee for British citizenship but her passport is expired and she won't be renewing it before we apply...can we still use her as a reference?

The current requirements for the referees are: (Source: Nationality Forms Guide)

One referee must be a person of any nationality who has professional standing.... The other referee must be the holder of a British citizen passport and either a professional person or over the age of 25.

So you should be able to use her as a referee of the first kind, but not second.