Good luck with your search, as it was a town mill there may be some records, many small mills, at least here in Herefordshire worked on a barter system, one sack of flour to the miller, one to the mill owner and the rest back to the farmer whose wheat it was.
Mills ground a lot of things, not just flour, crushing oats for animal feed, crushing clover among others.
It was a very skilled task and hard work, up three flights of stairs while the sack hoist is lifting a sack of grain, tip it in the hopper, adjust the feed rate, down to the next level to get the wheels set,
Down again to see what’s happening, collect the white flour that has been seived thro the silk screen,
Bag up the brown flour, collect the remains, then start all over again.
Mike