Three giants of the greased line--A.H.E. Wood, Frederick Hill, and G.P.R. Balfour-Kinnear--preferred the single hook to the double.
Anthony Crossley was a dissenting voice:
"Many extremely good fishermen, including two of Wood's own pupils, definitely prefer double hooks. For myself, in the smaller sizes I infinitely prefer them. Why? First of all because I never have breaks of the hook against the bone of the fish's jaw. Secondly, because it is not my experience that in slow water fish disgorge the flies before the current has tightened the line downstream of the fish. Thirdly, because in fast water where the dropper is of such value, I find they are much more likely to get a grip. Finally, the fish which takes the fly immediately below you (always the worst to hook), is, I think, rather more often brought to the gaff than on singles. Nor have I ever found any evidence that one hook levers out the other, and I think this could only possible happen in the very large sizes."
Anthony Crossley, 1939
It would appear that single vs. double hook is not a new debate......