Hi', Lads. The troubles with the old-fashioned across and down wet fly presentation with a taut line were inability to fish more than a foot or so of the water column in streams, drag, and a bite indication that was by touch rather than sight. Creating slack line in the downstream presentation permits the trout to turn with the fly in its mouth before it feels the resistance of the leader and line. Yes, on a tight line you will feel every little knock or bump, but so will the trout, and it's a pound to a penny that it will feel the resistance before the rod tip registers it or the line hand feels it. The push of the water on the arrested tight line will ether hook the fish or give a bump which is the pent up energy being released as the fly is ejected. A strike in many cases is just a secondary setting of the hook, or it comes too late.
I didn't fish daytime wet fly effectively until I was asked to teach a family of four children who were the grandchildren of the lady who owned our finest stretch of fly water on the River Eden, back in 1974. They missed many bites fishing across and down, and weren't sufficiently skilled to fish dry fly, which I always found to be easier and more effective. Lake fishing wet or night fishing for sea trout, I could manage pretty well. So, I had to find a method for the kids that eliminated tight line misses.
The two best wet fly exponents that I knew were my old woodwork teacher from grammar school who fished up and across with a long cane rod, and a 'high stick' rod position, and a colleague at my place of work who fished across and down with a slack line. Every trout that he caught took line off the reel, as Gwyn Parry, my old workmate, never trapped the line under his finger. He tightened into his fish as they were looking the other way, so he didn't pull the hook out of an open mouth, as the rest of us often did when we started fishing 'the easy way.'
I taught the three elder children to cast up at about 45 degrees, then raise the rod tip to take up the slack as the line, leader and flies came back towards them, keeping in touch with the team of wets. At right angles to the bank, as they tracked the flies, the team was fishing at about as deep as unweighted flies could be expected to travel, and at this point, they were fishing with the loop in the line that became their bite indicator. To keep the flies fishing at depth, they could lower the rod as they tracked the flies around, and at any time beyond the right angles point, if they checked the rod movement, they produced a lift which sometimes produced induced takes.
When trout are 'on the fin' taking ascending nymphs, it was often possible for across and down fishers using sinking lines to drift their teams of flies under the trout on station. It wasn't until the line swung around and tightened that the pull of the current lifted the flies into the fish's field of vision. Then, the tight line bite was a case of self hooking, tighten to make sure, or a ping and a mssed trout. A floating line presentation might have got around the problem.
I taught the children to watch for a draw on the line as they tracked it and the flies around, and to tighten by lifting from about the 60 degrees to the horizontal up to the vertical rod positon. They caught far more fish that way, and each cast was a longer engagement with the water than it had been previously. I thought I might have evolved a new style in 1975, but learned from watching a Gary Borger video tape, purchased in 1989, that the method was used in America, where it was known as 'The Leisenring Lift.' Using a sinking line, it is called, I believe, 'The Brooks' Method', or something similar.
So, no fame for TC there.


Or did I beat Larry Leisenring to it? He sure as eggs is eggs didn't copy me.


Hope that helps a bit. Cheers, TerryC.
PS Do I use the method -- very little, some people never learn!!