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.
Day of the Intelligence was a planned novella in the Lethbridge-Stewart series. Penned by Andy Frankham-Allen, the book was set to tell the origin story of the Great Intelligence. Due to personal reasons, the author had to pull the book from the schedule. Travers & Wells: Other Wars, Other Worlds served as its replacement.