I mentioned in the last entry that Black Orchid was the first pure historical in 15 years, but there is one major difference between this story and the historicals of the Hartnell and Troughton eras. In the early days, keeping the TARDIS secret was of prime importance for The Doctor and his companions. In Black Orchid, The Doctor not only tells others about his ship, he uses it's existence as his alibi.
To further help clear his name, The Doctor does the unthinkable and invites the entire local constabulary into taking a ride with him. The TARDIS is, once again, being knocked down a peg. It is no longer a mystical machine that only the very few people, personally selected by The Doctor, were allowed to transgress its dimensions, but merely another vessel in the Doctor Who universe, used to taxi people from location to location. Even its alien properties no longer succeed in impressing: all Constable Cummings can be bothered to utter is "Strike me pink!", before carrying on with his report to Sir Robert Muir.
In fact, everyone involved in this story seems to accept The Doctor's otherworldly talents with remarkable ease. My best guess is that such a well-to-do family as the Cranleighs would never be seen to be bemused or impressed by anything that they hadn't done themselves. To drop their collective jaw ever so slightly when witnessing the TARDIS dematerializing would be to admit failure to their peers.
Apart from the murders that The Doctor seems to keep stumbling on, it's actually good to see the companions have some fun for the first time in a while. Nyssa proves herself to be not quite the stick in the mud that she often appears to be, Tegan is adept at dancing and seems to have a thing for older men, and Adric even gets in on the fun by gorging himself at the buffet table instead of trying to dance. Black Orchid is the last chance for everyone to enjoy themselves before the good times come to a shocking end in the episodes to come...