Phil. There is no such thing as a Prep Step in the book. If we do it is outside the bar of music we are entering. That's fine it can be done, on the heel, or if you wish it can be BH. and should be much smaller than the first step, if you don't do it smaller you will take away from your first step. Once we get into the dance there is no Preperation Step.And I ask again which is the most important step?? . My opinion is it has to be the first step which in Waltz is on one. I was once told . If you painted a piece of metal with the wrong primer, everything that follows is going to be a failure. If we agree the first step, usually the heel lead in any dance is the most important. Then we must study without any pre- concieved ideas how it is being demonstrated. Your Andrew Sinkerson tape for instance. My teachers regually have lessons with Andrew, and will again pretty soon before the British. If you could have a look and see if the front leg is straight just prior to the weight arriving, and how flexed is the knee just before the body arrives. And also what part of the back foot is in contact with the floor at this point.I think you will find it is the very last part of the toe. I have a tape of a couple from the last IDFS World Titles performing solo the Foxtrot . When I stopped it at the point I was looking for, I see that the man's back foot is on the last part of the toe, neither knee is bent they are truly suspended in space. At the same time the ladies rear foot is also on the very tip of her toe. Their weight at this time is split weight. These are some of the things I look for, and then I ask. Just on that one step alone there is still more to put the magnifying glass to. Somebody will say, that's just one couple. I can honestly say that on that step I can't see any couple doing it differently.