John Smith’s parents and Joan Redfern’s granddaughter were named in honor of Sydney Newman, who initiated the creation of Doctor Who (and came up with the “bigger on the inside” concept), and Verity Lambert, the show’s first producer.

INTERN: You are a doctor yourself?
FOURTH DOCTOR: Well, sort of, yes.
INTERN: How do you do? Tell me, where did you qualify, if I may ask?
FOURTH DOCTOR: A place called Gallifrey.
INTERN: Gallifrey? No, I’ve not heard of it. Perhaps it’s in Ireland.
FOURTH DOCTOR: Probably.

— The Hand of Fear

WOMAN: Patient’s name?
LEELA: Uh, just the Doctor.
WOMAN: Place of origin?
LEELA: Gallifrey.
WOMAN: Ireland?
LEELA: Oh, I expect so.

— The Invisible Enemy

JOAN REDFERN: Where did you learn to draw?
JOHN SMITH/TENTH DOCTOR: Gallifrey.
JOAN REDFERN: Is that in Ireland?
JOHN SMITH/TENTH DOCTOR: Yes, it must be, yes.

— Human Nature