Geograph - photograph every grid square

on the OS map it is described as a war memorial A plaque on it refers to its refurbishment in 1994 and says it was 230 years old then. So, what happened in 1764 that made people build towers?

The only thing I can think of is the end of the Seven Years War (1756-63)
This little remembered war actually had a phenomenal effect on British standing in the world (to be dented a few years later by the loss of the American colonies of course). But at the Treaty of Paris Britain was ceded Canada, Cape Breton, Nova Scotia, Minorca, Tobago, St. Vincent, Grenada, Dominica, Senegal and (wait for it), Florida.

If your tower was in Northern Scotland I'd be sure it was a monument to this war as it was the first war in which Highland Regiments fought - but as it is in Wales the link is rather more tenuous.