Is there a word that means roughly 'someone who refuses to accept change and insists that things should be done in the old established way'? I'm looking for something like behind the times or has trouble understanding the flow, but preferably a single word - or stick-in-the-mud, which won't really do since I'm writing in a formal and slightly archaic style.
Reactionary: someone who opposes political or social progress or reform. Highly conservative and favours a return to an earlier, more disciplined, social order.
Diehard (variant spellings): first used on the battlefield in the mid C19th, then to describe Conservative politicians who were clinging to British imperial power in the 1930s. Now refers to someone who is staunchly opposed to change, even when there are good reasons for it.
One potentially useful term for such a person is a mossback. Wiktionary has a good definition of this term:
mossback (plural mossbacks) 1. A turtle that, because of its age, has a growth of algae on its back. 2. (by extension) A very conservative or reactionary person, especially one with old-fashioned views.
According to Merriam-Webster's Eleventh Collegiate Dictionary (2003), which dates the term to 1872, the original mossback was a fish:
mossback n (1872) 1 : a large sluggish fish (as a large-mouth bass) 2 : an extremely old-fashioned or reactionary person : FOGY
I recall reading back in the 1970s (in Texas Monthly magazine) that hardcore conservative state legislators in Texas (who in those days were almost all Democrats, and who were frequently referred to as "unreconstructed" because their views harkened back to those prevalent among white citizens in the antebellum South or during the Confederacy) were called mossbacks. Legislators who did nothing at the capitol but sit around gabbing with their fellow lawmakers or with lobbyists, on the other hand, were known as furniture.