I have given this some thought and finally come up with a theory as to why you may not have grease nipple holes on your steering column. The part number quoted in the parts books usually refers to a 1933 part but this was changed in 1935 when the extra plate below the damper was fitted to accommodate two damper discs instead of the previous single disc. The new steering crown from 1935 is easily identified by the slot for the bottom damper plate. Your steering column has this slot so it has to be from 1935 or later. Looking at the parts book for a 1948 Square Four the steering column has been redrawn, along with the rest of the page and doesn't show any bosses for the grease nipples. (Yes, I know that by 1948 telescopic forks were in universal use on Ariels but the girder fork details still appear in the parts book, along with the tele fork ones). So, my theory is that the grease nipples were omitted late in WWII to save costs on W/NG machines which were unlikely to survive very long on the battlefield and that your bike has, for some reason, been fitted with one of these steering columns.
Incidentally, I have a 1933 type column on my RH500 and a post 1935 type on my 4G. Apart from the bottom damper plate slot, another difference is that the post 1935 type has the grease nipples part way along the bushes whilst the 1933 type has the grease nipples inboard of the bushes. As a result, the grease applied works its way on the 1933 type very efficiently to the steering damper disc. So the second damping disc and the change in position of the grease nipples was a "belt and braces" approach to an ineffective steering damper.
36 4G, 37 VH, 54 KH(A), 75 Healey 1000/4, 52/53 ex ISDT KHA (project).
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.