So in the Gallifrey audio Annihilation, the Borusa of an alternate Gallifrey is played by Katy Manning. But since pretty much every single other character that appears in alternate Gallifreys is played by their original actor, AND Engines of War confirmed that Borusa was a woman at least once, it’s totally fair to assume that the Borusa of the Doctor’s universe had a Katy Manning body.
So imagine Jo Grant getting annoyed and snapping at the Doctor and/or the Master, and them jumping out of their skin because for half a second she was the spitting image of their old ultra-strict academy tutor.
Here are a couple of pics from the Radio Times 30th Dec 1972 to 5 January 1973 for “The Three Doctors” Check out the blurb in the first pic by Carole Ann Ford about Susan. The second pic shows her, Katy Manning and Frazer Hines doing a photoshoot for this RT issue.