Roots: The Book of Mark (Legion). The Hitchhiker's Guide to the Galaxy (see: Fluffs), The Doctor name checks An English Country Garden and sings a personalised version of Good King Wenceslas (the opening scene recalls that of the song's first verse, with the Doctor enjoying his role as the wandering nobleman)
Intertextuality: Among the alien races the Doctor mentions are the robotic Trods, the Dalek-analogues from TV Comic.
Fluffs: A possible mispronunciation of 'Vogans' by Tom Baker as "Vogons" may mean the Doctor is referring to the constructor aliens from Douglas Adams' The Hitchhiker's Guide to the Galaxy (rather than the gold-skinned enemies of the Cybermen in Revenge of the Cybermen)
Dialogue Triumphs: "Delicious and licoricey - just the kind of thing to drive a true doggie bananas"
"What are you but space vermin, a swarm of fleas hopping from one body to another? You offer nothing to the Universe - you can't even make honey!"
Continuity: the Doctor has set the TARDIS to find the Hornet here aided once more by an historical account, this time of monstrous wolves and swarms of flying insects. Tilling Abbey, where the TARDIS lands, is an impressive nunnery with battlements located on a hilltop overlooking a great forest. Inside its resident sisters brew whiskey, imbibing it to stave off the winter shills, although the liquor has the added side-effect of warding off the Hornets, who regard those who have [recently] drunk alcohol as being "contaminated". The Doctor thus deduces that the Hornets have thus far only possessed those who are tee-total. He has learned since the events of the last story that Angelica's grief-stricken brother has abducted his sister's body and had it embalmed, ensuring the survival of her feet and ballet slippers. He reveals that Ernestina married and lived a quiet, normal life, though the hornets lay dormant within her, unbeknown to him, and thus settled in her shy and solitary grandson Percy Noggins.
The Hornets have been on Earth now for three months, having travelled through space and discovered the planet by accident. They first entered the body of a pig which, possessed with an unearthly light in its eyes, has been taken in by the nuns of the Abbey and become their Reverend Mother. After the Queen of the Hornets leaves the pig it reverts to it animal state.
The TARDIS reveals many rooms, including several containing various form of portraiture (including holograms, multidimensional sculptures and watercolours), furniture (from Earth and Gallifrey), chamber music, laughter and other voices (some calling to him), and waterfalls. Two libraries are entered, one featuring leather-bound volumes and a great chair, as well as rooms containing an English country garden, a swamp the Doctor didn't know he owned, a sitting room to rival that of Napoleon's in Le Louvre palace, a laboratory, garage, tropical greenhouse, a galley kitchen and a lounge with French doors opening onto a terrace. Linking them all are corridors, galleries, walkways, stairways and escalators. The Power Room is the heart of the TARDIS - the Doctor knows a short cut from it to the console room. He calls the central column of the TARDIS console the 'time rotor'.
The Doctor's wolfhound 'Captain' makes his debut here as "captain" of the wild pack. Once the Hornets leave his brain he is almost immediately docile and obedient to the Doctor and, having devoured at least four crepes suzette, is presumably immune to the Hornets' influence due to the liquor in them.
The Doctor is carrying a small pen torch with him, along with his bag of aniseed balls purchased in Blandford (see: Links). His injured hand heals "with Gallifreyan efficiency". He recalls a brochure for a computer-assisted cooking course ("cordon bleu, of course"), which he has been undertaking in a small galley kitchen in the TARDIS.
Location: Tilling Abbey, Northumbria 1039, Venice 1768
Links: The Circus of Doom, The Dead Shoes. Malevolent alien races mentioned by the Doctor here include the Zygons, Axons, Nestenes, Kraal (The Android Invasion), Pescatons and Krynoids (The Seeds of Doom), the Mandragora Helix (The Masque of Mandragora), and Sutekh (The Pyramids of Mars)
The Bottom Line: "Can be unpredictable, nuns"
There's a sense of things finally cranking up a gear here, although precisely where things are going (apart from backwards in time - maybe) is yet to be heard. Descriptively though it's a treasure, with wonderful scenery and a bloody battle at the opening - and the TARDIS interior chase is very lively as well. And Venice - Ahhh! Venice! All helped of course by knowing that the conclusion isn't far away.