I've added the following passage as it's the only one I know of in all the books I have, but may well be others, though...
NOT necessarily the definitive work on the subject but IMO it explains it pretty well, as does that written by Mark Wintle................
I’m quoting from a book ‘ Successful Angling ( Course Fishing Tackle & Methods ) written by Messrs Richard Walker, Fred J Taylor, Hugh Falkus and Fred Buller and first published in 1977
AS FOLLOWS ;
Stret pegging ( Page 105 )
Holding back a trotting tackle to clear an occasional obstruction on the bottom sometimes causes the bait to rise up in the water in a manner thought attractive to fish. Stret Pegging was possibly developed because of this discovery. The method is old and well established, though there is no indication as to how its name is derived.
Stret pegging, or stretting as it often called, is a method used in near bank swims and is particularly effective in flood water. The tackle is set deeper than the water and is allowed to settle briefly downstream after casting. Then the rod is lifted, a yard or more of line paid out, and the tackle allowed to settle again. The procedure is repeated until the maximum downstream area has been exploited, at which stage the tackle is recast.
It really is a combination of near bank trotting and laying on tactics ; its effectiveness lies in the fact it covers big area of water at all depths – slowly and methodically. While the rod point is being lifted the tackle rises from the bottom and the bait may even show on the surface. A bite could come at any depth. While the rod is in the rest, where it stays between moves, the bait spends most of its time on the bottom, but is subject to sideways movement as the peculiarities of the current sweep the float out from the back and back again. From the bank to several feet out of the water is therefore covered effectively throughout the whole length of the swim, at all depths.
The float lies at half cock when resting and throughout the whole time the line is usually taught from bait to rod tip.
Bites may be registered by the float moving sideways ( difficult to recognize at times ), lying flat, or diving under so that the rod tip bends toward the water
END
( I believe this section was written by Walker, but I’m not sure )
Make of it what you will..............