Adventures in a Pocket Universe (series)
From Tardis Wiki, the free Doctor Who reference
Adventures in a Pocket Universe were two audio dramas released by BBV Productions under their Audio Adventures in Time and Space banner.
These two audio dramas, The Choice and The Search, featured John Leeson as yet another version of K9 and Lalla Ward as "the Mistress" (heavily implied to be Romana II) travelling through Ecto-Space (heavily implied to be E-Space). The series had to tread a very fine legal line, since their only license was derived from Bob Baker and Dave Martin, co-owners of the character of K9. Thus, almost every narrative element is either original to the series, or, like "the Mistress" and "Ecto-Space", a close but legally-distinct approximation of a televised concept.
