This is confusing to me. Scott 34 (SG 79) is the 4 pence version with large garter. I've verified the watermark on these examples. Scott 34b (SG 81/82) is listed as the same watermark, but with hairlines in the corners. However, my copy of Stanley Gibbons attempts to help clarify with a small note:
"4d. Plate 3. No hair lines. Roman I next to lower corner letters.
4d. Plate 4. Hair lines in corners. Roman II"
I'm pretty confident about this one, as I see the hairlines, and a clear Roman II in the lower corners.

But now I had to look twice at this other one that I thought was also 34b, hairlines, in all four corners. What I don't see is the Roman II, unless it is inked over?

This is further annoying me because stamp #3, which I purchased as a Scott 34, no hairlines, seems to have a small indication in the upper right, but is clearly Roman I.

So what indication should I be using? Seeing one or more hairlines, or seeing Roman I versus II? Just wondering.