You know, I've thought about this a lot, and I disagree.
If you move your foot/leg backwards, your center of gravity moves backwards. That is exactly what you want. Your parnter will/should move to follow your center, moving her center forward.
Now, if you DON'T want your center to move, you would have to lean forward, but that's not what you are doing here.
Well for once, Steve, I rather think UKDancer's is the right description.
The body/chest must move backwards first, and the leg then projects
to the correct place for the body to centre over it.
If you just project the leg without moving, the body must move very slightly
forward to balance the extended weight. But in practice that is not how
we should move backwards because it would give no intent,
even the wrong intent, to the woman.
When a woman is moved backwards she responds to her body movement
and projects her leg In the man's case he moves his own body backwards
and then his own leg responds.
I would add for Mario that practising this alone is quite difficult and for
solo practise to have any usefulness you really do need to ensure
you move your body first, and backwards of course. It is just not natural
as we don't do it in real life.
Oh and by the way, I do walk backwards and comments are often about
how rare for a man that is. But my walking backwards is invariably down
the line of dance so you have to know how to turn, look and note where
everyone is and the conditions have to be right.
One other thing, in walking backwards you really do need to get your leg
out of the way of the woman's leg coming at you. So don't delay as you
might walking forwards, this time your leg should move at the same
time as the woman's and the step should seem longer than one going
forwards even if the distance actually moved is similar.