Thanks everyone this discussion has helped a lot! I'm now getting nice results more consistently, which is partly down to improved dexterity, but the massive improvement in quality of surface finish is clearly down to improved tool sharpness.
I have noticed that the 1¼" skew I use for roughing and gross shaping gives less pleasing results than the ½" skew I've been using for shaping beads. The larger one has been ground with a straight edge to meet at about 40° and seems quite friendly in use, the little one was rusted to hell with a trashed edge when I found it, That's been re-ground to a curved edge (gentle near the bottom, becoming pronounced at the top), with a 15° to 20° meeting angle, the finish is far better, but the tool requires far greater concentration to use.
I have noticed that the 1¼" skew I use for roughing and gross shaping gives less pleasing results than the ½" skew I've been using for shaping beads. The larger one has been ground with a straight edge to meet at about 40° and seems quite friendly in use, the little one was rusted to hell with a trashed edge when I found it, That's been re-ground to a curved edge (gentle near the bottom, becoming pronounced at the top), with a 15° to 20° meeting angle, the finish is far better, but the tool requires far greater concentration to use.