From InquisitionWiki

Gentry are those freemen who have amassed enough wealth to leverage themselves into the lifestyle of the nobility, though not the title. Frequently, nobles resent them, but are often forced to embrace them. Gentry tend to be very socially conscious of the precarious position in which this places them, with money and the power that comes with it, but no specific law-granted rights to either.

Gentry Professions

Attendant  : a personal assistant, often given very specific tasks to look after.
Banker     : owned or worked in a bank.
Castellan  : resident owner or person in charge of a castle (custodian).
Chamberlain: responsible for the great chamber, & personal finances of the castellan.
Herald     : knight's assistant and an expert advisor on heraldry.
Landowner  : owned land, often rented it out for a percentage of what was produced.
Steward    : took care of the estate, supervised the household & events hosted in the hall.

NOTE: These are common professions for the gentry class, but they are not restricted to that class alone.

Rise To Legal Social Class

Those citizens who have no hereditary titles, but receive a minimum income of 2000 silver per year, with no labor to their hands as well as knights, the ordained clergy and the second (and later) children of titled nobles, shall hence forth be officially recognized as Gentry. Additionally as part of this recognition, the gentry are now permitted some of the lesser rights of the nobility, such as limited sumptuary and the use of ab as a prefix to their family name. Finally, they are also permitted to marry the nobility with a writ from the Crown.