Thanks for the input guys.
I coincidentally did finally receive a response this morning. Unfortunately it was way worse news than I was expecting.
They state that due to a single episode of what they refer to as delusional and paranoid thought over four years ago, I am assessed as unfit for all classes of medical certification. The letter is very short, with nothing in there about what I need to do next to regain certification (other than the standard line about appeals).
The episode was very brief and coincided with an extremely difficult period in my life, during which I was not flying. The symptoms never resurfaced and the ensuing CBT treatment was aimed only at the OCD-type symptoms that endured thereafter. There was never any official diagnosis of paranoid or deluded thought by any of the specialists I saw after the episode either.
I am just waiting to hear back from my AME regarding the next steps, unfortunately they also have proven quite difficult to get in touch with. The AME who issued my class 2 was much better.
Anyone have any experience with appeals and how long they take?