Right, had a wee play.
Stripped natural quill, wound with spaces left to let thread show through, almost use the herl as a rib, keep it even and you get pretty close.
Looks quite nice in orange
Doing it in Touching turns, make a nice quill body, but doesn't look like the fly you want.
I tied in the herl by the tip and then made a smooth underbody with one layer of silk down to the bend tying in the herl, and one back up to the head.
Then in open turns wound on the herl, once its varnished it looks smooth.
I reckon the Actual fly is done using synthetics as a natural herl tapers and the photo of the fly does not
Sandy