"The action of the two hands together exerts pressure on the right [trail] elbow, forcing it more towards the centre of the body. The elements of this movement can be simulated by standing with the right arm well across the body and the palms together, horizontal to the ground. If the right hand is pushed backwards from the wrist by the left hand, the right elbow is immediately forced more across the body."
Blake intended this to be a demonstration (not a drill) to show the reader that the concept works. I wonder if a drill could be developed to simulate this forcing of elbow across the body. Of course, in a golf swing the hands have the club "between" them. When the hands are holding on to a club shaft, they relate and work differently than simply the two hands against each other as in Mindy's demonstration. Thus I would think that such a drill should involve a club shaft, not just the two hands together. Perhaps it could be combined with a drill to help learn the grip change.
Chris Walker, of England, often stresses the obsolute necessity that the trail elbow be pushed across the body during the backswing. I think it would be very useful if a drill could be conceived to help the Blake learner ingrain this essential move. Jim