You can get the jist of what Bonar instructs from an old Golf Magazine article (http://www.golf.com/golf/instruction/article/0,28136,1565175,00.html). In it, Bonar claims that ALL of the teachers have taught the wrong thing and that his turning over of the wrists at impact (or as he says, imagine the clubshaft is a screw driver and you are screwing the shaft into the ground counterclockwise --- for a righty-- right before impact).
Here's a sequence of what it looks like according to Bonar:
Personally, I don't feel like I'm learning quite exactly the thing Bonar is teaching. Bonar teaches a right handed turnover (if you're a righty). I don't care for that move because then you start getting into a too dominant of your right hand and it's flip-city. I more or less think of rotating the left hand.
Secondly, I don't try to actively bow out the left wrist at impact. Lastly, Bonar wants golfers to cup their wrist at the top of the swing to open up the clubface. I have a flat left wrist at the top of the swing.
So no, I'm not exactly doing what Bonar teaches.
But this type of swing has been around for quite some time. It's the good ole 'swivel release' that a teacher like Ben Doyle (and many others) like to incorporate into their instruction and was written by Homer Kelley in 'The Golfing Machine' all the way back in 1968.
Here's Ben Doyle incorporating the swivel release in his very own swing:
Lately, I've grown really tired of many golf forums because the threads about golf swings and golf theories usually turn into long, worn out flame wars.
Unfortunately, I think Bonar exemplifies part of the problem.
I think a lot of the problems with discussing the golf swing is that most golfers usually come from poor instruction early on in their lives. Then the golf magazines just compound the problem. Eventually the golfer gets some better instruction, but the teacher is teaching one particular pattern. Usually, it doesn't work for that golfer. Eventually the golfer gets some different instruction and finds a way to swing the club that works for them.
After that, the golfer thinks that because a certain method worked for them...it will automatically work for everybody. And to make matters worse, they believe that there are a lot of absolute imperatives to the golf swing that all golfers MUST do in order to hit the ball effectively.
Thus, you get a lot of golfers with a lot of different methods about how to hit the ball effectively and the flame wars begin.
And yes, I've been guilty of this crap as well.
The truth is that there are very, very few absolute imperatives to the golf swing. Flat lead wrist at impact and effective pivot are probably the biggest two 'must have' parts of the golf swing. But other than that, there's tons and tons of ways to grip and swing the club and still be a darn good ballstriker.
Bonar falls into the trap. He believes that this is THE secret to golf and that everybody else has neglected to tell golfers that. And what's really bad is that he doesn't really instruct the method very well nor does he seem to know much about it.
Thus, the hatred and criticism begins and there's little in the way of good, meaningful discussion of the golf swing.