Congratulations on what must have been a gratifying round. Any round in which we find out something essential about our swing is gratifying--score not bad either. Keep us apprised as to whether this continues to work for you.
I've always had more difficulty with longer clubs when using my version of Blake's swing. From the wedges up through about the seven/six irons the steeper plane seems to work fine, but with anything longer results can be very poor indeed. The feeling I get is that everything would be cool if only I were about a foot taller and could swing my driver with the same steeper plane of my eight iron.
When I wrote Mindy about my longer club problem, he replied, "I get the same feeling with all clubs." Of course, he hit longer clubs and driver equally as well as his shorter clubs. If you have viewed the Richard Wax video, then you know that he swings on a flatter plane than Mindy's books seem to suggest. Maybe some fine day in the not too distant future we'll have the opportunity to see Blake's swing on film. My memory of his swing is now quite dim.
Mac, I must ask: What do you mean by "I decided to ease off and simply concentrate on the arm/shoulder action and let the legs look after themselves..." and by "...no apparent effort or straining of the lower body," and by "After today with less thought of the leg action and more concentration on a slow relaxed arm action..."? As you know, "less thought of leg action" and any thoughts of conscious "arm action" would be anathema to Blake. Richard's leg action is "with little appparent effort" but he still emphasizes the importance of legs to his swing. Are you saying that your first move down is no longer (from GTTB): "...a horizontal rotating movement, led by the legs, which drags down the hands..."? Are your legs dragging the hands down or are you moving the club with your arms and shoulders? But, hey, even if your swing is not true-blue Blake, maybe you've found something that works for you.
The main trouble I've always had with my version of Blake is repeatedly maintaining the connection between lower and upper body. I experience this problem with both short and long clubs, though worse with longer clubs. I eventually decided some small change in my ADDRESS from swing to swing may be the problem, rather than a minor change in my MOVEMENTS from swing to swing. In yet another effort to solve this dilemma I carefully studied figures 9 and 10 in GTTB. I see that set up as follows: (1) substantially open--about 45 degrees, (2) trunk and knees well bent, (3) head well back behind the ball, (4) hands well forward by lead knee, (6) spine tilted slightly away from target, and (7) clubhead directly behind the ball. The stance I had been using was at variance from this, mainly the position of my hands. Just before beginning the backswing I "twist the rubber brick." This move closes the shoulders a little, torques the body more, and, importantly I think, ensures a bit of spinal tilt with head well back. Trail knee feels as if it is "jutting out" or "prominent" or, even, "in the way of" the backswing.
OK, as Mindy says in GTTB, with the hands forward by lead knee, the first part of the backswing, or takeaway as he calls it, move the hands parallel to a line through the (open) toes or "out" if you will. Notice that the clubhead moves along the target line (extended backwards) because the lead arm/club shaft is "folding", ie, angle between lead arm and shaft is becoming more acute and lead hand rotates in a closing direction (Blake would say "staying square"). As the hands pass the trail knee move them along the target line extended backwards ALL THE WAY TO THE TOP. My feeling is that my hands are taking the club higher and moving along the target line extended backwards. This will preclude lead arm coming too much inside. I've been practicing with a target line extended backwards in chalk on my practice mat. As always I do a grip change during the backswing and my backswing is deliberately slow. Once I start moving the hands along the target line extended backwards, I give no thought to steepness of plane. I simply take the club to the top, ie, until lead shoulder is under my chin. Trail knee does not collapse in backswing. This is definitely more repeatable and feels powerful, but has only been done on my deck without a ball. I'll try it at the range within the next few days. Jim