The Osterhagen Key was a device that was held by UNIT by the time of the New Dalek Empire's invasion of Earth.
After the planet fell to the Daleks, UNIT gave the key to Martha Jones who was to use Project Indigo to escape. Former Prime Minister Harriet Jones told Martha Jones never to use the key. (DW: Stolen Earth)
Word root possibly means "Eastern City" or "Fossil City", depending on spelling.
"Osterhagen" is an anagram of "Earth's Gone"
Rumours
- Assuming the ambiguous theories of a 'botched regeneration' are plausible, any chance we could be seeing an early version of the Valeyard? In Trial Of A Time Lord, the Valeyard is seen as an incarnation of the potentially evil side of the Doctor between the twelfth and thirteenth regenerations. Though a couple of regenerations early, the "Osterhagen key" roughly translates as 'graveyard' or 'boneyard' (insults that the Sixth Doctor used against the Valeyard in 'Trial Of A Time Lord').
speculation : http://www.leytonjay.co.uk/sci-fi/what-is-the-osterhagen-key
