One of the most famous golf instructors of the early 1920s was Ernest
Jones, working out of an indoor studio in Manhattan. He lost one of his
legs during World War I and this led him to develop the method
"Swing the club head" in the book "Swinging into Golf".

A seemingly contradictory method was introduced a little later by an instructor
called "Little Pro" - Eddie Merrins. Merrins. who is Emeritus Professional at Bel Air Country Club imparts a method called "Swing the Handle" and can best be described as a double-fisted tennis backhand.
My reflection is that Jones grew up with hickory clubs and Merrins
with steel.