Trumpton

Trumpton was one of the fictional locations within Storyland. Shortly after landing in Storyland, the First Doctor saw Sherlock Holmes walking past a sign giving the direction of Trumpton, Mordor and Lilliput, one of several clues which allowed him to realise he had retuned to Storyland. (COMIC: Nostalgia Corner)

In non-valid sources
To be added

Other matters

 * While Mordor and Lilliput are both literary references, Trumpton is a reference to a BBC children's programme which ran contemporarily to Doctor Who itself in the late 1960's. The series officially crossed over with the DWU in the BBC charity programme Future Generations.