Hmm, if I recall the Act of Tilting (135 AB) by the Attire Assembly:
' A top hat should be worn no more askew than 30 degrees- further tilt compromises the stability of the hat, and threatens embarrassment. Furthermore, one shall be considered a rascal and a lout if any more than 27 degrees is taken. It is in this Assembly's view that the wearable range of a top hat should be from 3 to 23 degrees, to avoid negative remarks completely.'
However, if we reference the publications of John Tuxington (When in Vyshtorg, circa 197AB) , he concludes the tilt depends on, and displays, a person's social stature and age:
'Taken on average, the top hat decreases in tilt the older the wearer is- this may be a necessary change, as due to the increase of length (clearly the man must increase in wealth and therefore buy finer, and larger, hats) the angle must be reduced to retain stability. However, such conclusions ignore the blatant contrast in tilt seen in our youth and our seasoned. Youths can be seen with tilts of up to 25 degrees, with the average pertaining around 22. On the other hand, the most experienced among us can be seen at anywhere between 7-2 degrees, with a minimum recorded of 0- however, in this case it was assumed by all present that the elderly fellow felt the need to compensate for one of his appendages.'
I'll continue my research further, but nothing has been written closer to our time period, it would seem.