Gracie Fields

Brenda once thought that Iris Wildthyme resembled an "unholy blend of Gracie Fields and the Pendle Witches". (PROSE: A Tingle of Happiness)

Behind the scenes
Gracie Fields was played by Katy Manning in Baker's End. Manning also played Iris Wildthyme in Big Finish's Iris Wildthyme audio dramas, so the reference that Iris Wildthyme looked like Gracie Fields was a subtle yet effective way to describe Iris Wildthyme, who despite being the most recurring incarnation of Iris Wildthyme, is often left without much in-universe description. It was also a way to reference Iris Wildthyme's looks with mentioning an in-universe Katy Manning, though this not out of the ordinary.