Invincible 26.6 kts
Inflexible 26.5 kts
Indomitable 26.1 kts
This should be the mean of 4 runs at full power for the measured mile. Successive runs should be in the oposite direction.
I am unable to cross reference sources so please treat with caution.
I have the same numbers but, I do not have the tonnage at which the ships ran the test. I do however know the draught they did it at and that should give us a better idea of how heavy they were on that day.
Invincible, for example, got the aforementioned results at 25ft 2in fore and 27ft aft for a mean of 26ft 1in, if we take into account that her mean deep loaded was 29ft 9in we can easily conclude that she was nowhere near her max and very lightly loaded (N. Campbell). In fact according to Conways her mean at normal is actually 26ft 2in, so she would have been slightly (80 or so tons) under her normal displacement on the date of the trial.
So it is likely that the conditions for the trails in the RN and KM (as delcyros indicated) were similar until the start of the war, that is, normal displacement using Welsh coal which, of course skews the results of the KM ships requiring a reasessment.
Anyone has and idea of how much the coal difference would affect that speed? We know that the 27,4kn Von der Tann could at least raise the steam required for 26kn with very bad coal, so that would be her bottom line. If 26kn is indeed VdTs max, then she would be slightly faster in service than the first batch of Is and probably evenly matched with the second (longer hulls and more shp).
Regarding the 9,2in gunned ship, well, what if then someone made an Invincible-like ship then? The RN was trying to jump a generation and make the best AC possible in order to preempt such a move, they failed only because the KM made a much better ship than they believed possible just a year later; that and the appearance of hard capped shells which rendered the Is protection obsolete.