Second paragraph of third story (“The Time Thief”):

The secret of this huge ornate building was a NuSev technical innovation, known as a holo cloak. The entire exterior of the museum, was, in fact, a massive 3D virtual reality illusion, projected across the building by tiny holo emitters, dotted around the building’s base, ensuring that it looked like a solid bygone age structure when seen from afar. The truth of the building was only revealed when visitors entered it, disrupting the light emitters. Walking in, visitors found themselves in a massive hall made of marble and artificial sandstone. Upon entry, visitors were required to wear holo glasses so exhibits could be viewed clearly, even though in reality they were all held in high security light box cages.

A modest volume of four short stories featuring K9 Mark 1, subsequent to his Australian adventures. For two of the stories Baker revives other Whoniverse creations, namely Axos and Drax, and the Axos story in particular is an interesting revisiting of the concept. Bt in the end there’s not so much to see here; K9 can never progress much as a character, so it’s really adventure-of-the-week stuff. Out of print, I’m afraid.