RHS front wheel bearings cleaned up and about to re-greased. In comparison, the LHS ones were found to be dull and not nearly as smooth, which meant that was the problematic side. This bike has rim brakes, and the wheel rim is probably approaching it is wear limit. Replacing those bearings would only be worthwhile if the other bearing surface were good and you were to replace the rim.

(Note for self, 12 ball-bearings on each side, and the diameter of the worn ones was circa 4.6mm.)