"The pertinent question is "were they given a fair trial"

Some of the people conducting the trials has also been involved in suppressing the rising. This I believe is prohibited in the military manual.

So question 1. Is it prohibited in the Military Manual that an officer involved in an action cannot take part is any later legal proceedings. A simple yes or no answer will suffice.

So question 2. If the answer to question 1 is yes then should these people have been debarred from being involved in the trials. A simple yes or no answer will suffice.

General Maxwell took it upon himself to conduct the trials in secret and without a defence being allowed.

So question 3. Was this ruled illegal by Crown Law Officers, again a simple yes or no answer will suffice.

To answer your questions in reverse order and acknowledging the fact that Martial Law had been declared on the 25th April and therefore taking into account that that significantly altered the circumstances to the extent that peacetime and civil rules are dispensed with:

3: No, and there was no such ruling, it was the opinion of some Crown Law Officers, the subsequent Royal Commission into the Easter Rising did not rule that the Courts Martial held after the rising were illegal.

2: No, if under the circumstance these are the only officers of suitable rank immediately available, and that holds good irrespective if martial law has been declared

1: No, see 2 above.

Your pertinent quest "were they given a fair trial"?

David Kent certainly received a fair trial (IMHO he should have been executed as an accessory to murder).

William Kent certainly received a fair trial - he was acquitted (IMHO he should have been executed as an accessory to murder).

90 people court-martialled and sentenced to death - only 15 sentences actually carried out - So yes IMHO considering what they were guilty of they received a fair trial.