Amazonia

Amazonia was the Earth delegate to Peladon when it applied for membership in the Galactic Federation.

Biography
Amazonia was however delayed en route, and did not arrive until after the situation on Peladon had resolved; her role having been taken on by the Third Doctor and a royal observer named "Princess Josephine of TARDIS".

Amazonia tried to explain to Alpha Centauri, Izlyr and Ssorg that she was the Earth delegate, and not this mysterious person they spoke of called the Doctor — asking "Doctor? What doctor? Doctor who?" She arrived in the delegate conference room where the TARDIS was, along with Alpha Centauri and the Ice Warriors, just in time to witness its dematerialisation. (TV: The Curse of Peladon)

In 3950, Amazonia was succeeded by Mavic Chen as the Guardian of the Solar System. (PROSE: Legacy; AUDIO: Neverland)

Behind the scenes

 * Amazonia is never referred to by name in the on-screen dialogue; her name is given only in the closing credits.
 * Amazonia is also unnamed in Brian Hayles's novelisation of the story, being referred to as simply "the lady Earth Delegate" and "Madam Chairman".