If your grandfather clock has a brass dial, it was probably made in the period between 16.
The early brass dial clocks only had one hand, because the average person had no need of knowing the time to the nearest minute, and with a bit of practise you can tell the time to the nearest five minutes on one of these early (and rare) clocks.
English clockmakers crafted clocks with brass dials from about 1680 to 1770.
One-handed clocks continued to be made in country areas for a while after 1730.
Our Reading List includes the main references, and most of these books are available from specialist booksellers or libraries.
Be careful here: the forms of cases and dials changed very gradually according to local fashion and subtle differences can be very significant.
These earliest oak cases were simple by intent, partly because London styles (which they copied in simplified form) were themselves still simple, but partly because there was little point in offering a clock in cheaper materials if the sheer extravagance of styling made it into a costly clock anyway.
Fruitwood and solid walnut were sometimes used as alternatives to oak at about the same price, but these woods were very prone to worm, were not too popular, and have far less often survived. An early eight-day longcase in oak, made about 1730 by Stephen Blackburn of Oakham, this one an arched dial clock with imposing caddy top, much in the style of a London walnut clock of the period. The earliest longcase clocks (let's say about the year 1700) were made in eight-day form, but also, as country versions, in thirty-hour form, the latter being about half the price of the eight-day.
The next step is to decipher the name that is painted or engraved on the dial face and see if you can find it (or something similar--spelling was informal, at best) in the makers' listings in Watchmakers and Clockmakers of the World by Baillie or Loomes.