George Morris created the crest release, for beginner riders or riders who cannot support their upper bodies through their lower legs.
No, Vladimir Littauer and Gordon Wright developed the crest release and first taught it to their students at their riding school, which consisted of suburbanites who could only ride on weekends but still wanted to hunt and compete. It was their solution to the practical problem of how to help this type of rider jump without abusing their horses. You can actaully get a copy of Gordon Wright's Learning to Ride, Hunt and Show
that has an excellent explanation of it. (Or of course, any of Litteaur's books.)
George Morris was one of Gordon Wright's students.
(Littauer lived 1892 - 1989, Wright lived 1903 - 1990, Morris was born in 1938. They were teaching the technique in the 30's, literally before Morris was born)
George *is* responsible for popularizing the crest release and through his very dominant influence, making it standard in the US hunter ring.