"Anonymous. Propulsion comes from the knee and thigh of the standing leg. Anne Lewis several times British Champion.
No, you - and Anne if she actually said this - are mistaken.
The primary propulsion comes from gravity. In coordinated dancing, you try to maintain your energy level as constant as possible, and preserve it by converting it between potential energy of rise, and kinetic energy of movement.
There's a specific relationship between body speed and altitude that needs to be followed for efficient dancing. Lower below this curve, and you are wasting effort. Rise above it and you are wasting effort.
As a result, the correct rise and fall (and knee bend) is not absolute, but can only be determined in the context of the body speed (travel per unit of musical time) you hope to achieve.
If you simply copy the rise and fall of a championship dancer without also achieving their body speed, you are making a serious mistake - you are not dancing like them at all, because the fundamental proportion at the heart of their dancing has been broken in yours. On the other hand, if you both lower less and move less, then you could actually be dancing the same way as the champion, because you have the same relationships in your dancing as are at the heart of theirs - only the scale is smaller in yours.