We also have canonical 10KTd destroyers by 1116. Destroyers big enough to carry small spinals. (Not that the Escort Destroyers in FSotSI have them - instead they have paired high factor bays.)
I've already explained those away. They are the "some escorts" mentioned as included in the count of combat vessels. They are also quite rare experimental designs and amounts to very few all told. (Note: This is my handwave to explain what I regard as awkward canon, not canon).
I found some interesting information in T20's Fighting Ships...
Thank you, such quotes are very helpful as I do not have
T20:Fighting Ships. (Indeed, I hadn't realized that there was a T20:FS at all).
It looks like the author didn't like some of what FS and RbS had established about the Imperial Navy and decided to ignore it. It is not surprising that the same attitude shows up in SF (since it's the same author).
My attitude is that every little bit of information added to what we already have makes just a little bit more. Anything established about the Imperial Navy
that doesn't contradict other bits is welcome in my book. RbS already opened the door for escorts (or destroyers, if you insist) bigger than the maximum established by FS, so those big destroyers don't faze me. The destroyers with spinals are more of a problem, since by definition they would be cruisers. Unless one takes the phrase "large spinal weapons needed to cause serious damage to a large armored ship" to mean that there are spinal weapons too small to cause serious damage to a large armored ship. Until now I've always thought that even a Factor A spinal could cause such damage, but perhaps not; that could be the reason for ships with spinals that are nevertheless not categorized as cruisers.
Another handwave would be that this describes practices in 990 and that such practices could have changed between then and 1105. Perhaps in connection with the IN changing over from being mainly TL14 ships to being mainly TL15 ships. I suggest that most of those spinal-mounted big-ass destroyers were simply phased out.
(Sadly, the same handwave cannot be applied to SF.)
Here's another bit of explanation to reconcile some conflicting canon that I just came up with: The term 'escort' used to be used to distinguish between different roles (e.g. 'Escort Destroyer' and 'Fleet Destroyer'). At some point between 990 and 1105, some Lord High Admiral at Capital decided that "henceforth all combatant ships smaller than cruisers are to classed as escorts, regardless of their designated role". Military types being notoriously tradition-bound (they are, aren't they?

), some ship designers are
still ignoring that decree when coming up with classifications for their ships. Hence the confusion in the use of 'escort' and 'destroyer'.
What TL is the
Perisher Class fast dreadnaught? If it's TL15 and if it's any good, it (the class, not any of the original production run) might still be around in 1105 and be helpful to Drakon.
Desron is also used in GTIW (p. 59).
While I appreciate your willingness to consider
any GT material worth quoting, I don't consider the Interstellar War setting to be authoritative when it comes to the Classic Era setting.
Hans