[EdZ]

But if the left palm is on the plane, and the left shoulder is not, then neither is the left arm, hence there must be an angle between the palm and the arm - how can the left wrist be flat?

Or is it to do with the subtle anatomy of the hand (I must look like an idiot sitting here at my desk cocking my wrist up and down - my wife is always telling me to stop forming golf grips and the like when we're in public together!)

Thanks,
Chris

Imagine you are rolling your left arm up and down a plane board the would rest under your upper arms at address. You are 'hugging' the plane, the wheel, - clapping your hands on it. Rotation takes place around this point if you turn and roll the forearms, back and through. Hitters tend to resist the natural 'roll' caused by the clubs design, and keep the back of the left hand more perpendicular to the plane in 'feel'. A frisbee toss motion for example. See the drills section for a few more examples.