16) Doctor Who and the Pirate Planet, by David Bishop with Paul Scoones
This is one book you won't have to buy; it is available on-line here, the first (in internal chronology) of the five "missing novelisations" provided by the New Zealand Doctor Who Fan Club, and the first of David Bishop's contributions to the extended canon (see also Who Killed Kennedy and the second series of Sarah Jane audios).
Bishop has added a few original touches to the Douglas Adams script, but unfortunately his own writing style was still pretty rough at this stage of his career. He certainly has improved since, but this was a wobbly start.
17) Doctor Who and the Stones of Blood, by Terrance Dicks
A standard Dicks write-what's-on-the-screen treatment, somewhat flattening a rather good story.
18) Doctor Who and the Androids of Tara, by Terrance Dicks
Another standard Dicks write-what's-on-the-screen treatment.
19) Doctor Who and the Power of Kroll, by Terrance Dicks
The Dicks/Holmes combination is a rather uneven predictor of quality, so it is worth noting that while this is generally considered the weakest of this season's televised stories, it is possibly the best of the Key to Time books, with the background to the Swampies, Rohm-Dutt and the refinery staff filled out a bit. Basically the only one of this season that I would recommend to the casual collector as opposed to the completist.
20) Doctor Who and the Armageddon Factor, by Terrance Dicks
Again, Dicks doesn't add much to what we saw on screen (with of course the added constraint of cutting six episodes down to Target size) and the weaknesses of the plot are consequently more visible.
The biggest disappointment of this run is that Mary Tamm's elegant, smart Romana doesn't come across as especially interesting on the printed page. This is no doubt due to a combination of factors - the general phenomenon where the brainy companions seem to come across less well in novelisations than the screamy ones, the fact that we're now in the period when Terrance Dicks was churning the books out at a rate of one a month or so, and perhaps the very visual presence of Mary Tamm - it seems to me a bigger contrast between impact on screen and on paper than for any character since the First Doctor.
Anyway, on to Romana II now. (And I am past the two-thirds mark for this insane project.)