Alpha Centauri Five

Alpha Centauri Five was a planet in the Alpha Centauri system. In 2157, an Earth Embassy was opened there at the same time Sifranos had been attacked by the Daleks. (PROSE: Lucifer Rising)

The Third Doctor told Jo Grant that he learnt how to communicate in Delphon whilst on Alpha Centauri Five. (AUDIO: The Havoc of Empires)