Therefore, its known narrative elements are not a part of the Doctor Who universe as we, on this Wiki, choose to define it. It may have been the basis for a similar story in another medium, however — and that story may indeed be valid.
The Imps was an unproduced Second Doctor serial written by William Emms. It would have featured imp-like aliens and vegetables which attempted to destroy a space station. It had to be rewritten to accommodate Jamie McCrimmon. Emms became ill and had to rewrite again to feature the loss of Ben Jackson and Polly. The story was postponed and replaced with The Underwater Menace. He eventually gave up and The Faceless Ones was written as a departure story for Ben and Polly.