TARDIS holding ring

The TARDIS holding ring was a section of the Doctor's TARDIS where he stored the accomodations of his companions after they had stopped travelling with him. It included the rooms of Susan Campbell, Ian, Barbara, Vicki, Steven, Dodo, Polly, Ben, Jamie, Victoria and on, till the last of Tamsin. Moreover, before the space for Susan, there was a room expecting for her son Alex Campbell. After an accident with a Blitzen fish, the Eighth Doctor deleted all the rooms but one. (AUDIO: Relative Dimensions)