I submitted an example of the commonwealth war graves to 'Fonts in use' and they decided it was essentially lettering. I have no particular feeling on this, just general interest. The link to read  is here.
The designer of the lettering is MacDonald Gill, Eric Gill's younger brother.
So do you feel the letters used on this memorials are fonts or lettering or an ambiguous place in between?

 

It is indeed an interesting case. 

On one hand there is an alphabet in digital format. On the other hand, as it happens for CAD monoline fonts, it doesn’t seem to have outlines: the final shape of the letters is determined by the tool and technique used to carve the stone (which is typical of lettering).

It’s a lineage that predates and runs parallel to traditional typography, with obvious mutual contaminations and blurring of the differences between the two throughout the centuries.

In there I would put things as diverse as sign painting manuals, CAD fonts, and vector alphabets, but also parametric fonts (thus, in a way, also variable fonts).