[Law] South Africa vs England 16/06 - Obstruction during maul?

[Jason R]

At around the 28 min mark, England have a line out in their own half. Ball is thrown in, taken by an English jumper and a maul is setup/formed. A few secs later the referee (Roman Poite) blows up for a PK against England, signalling for some kind of obstruction, and appears to say "walking back - obstruction".
I've watched it back a couple of times, and I'm not seeing the infringement he blew up for, so wondered if someone could enlighten me to what I must have missed?

 

[chbg]

Didn't see it (so what's the point in my posting, you may ask), but it sounds as if the ball carrier moved backwards through the maul. From a couple of seasons ago the ball had to be passed back through the maul, not taken back.

Although I'm damned if I can't find the applicable Law!

 

[Jason R]

Yup, you are spot on. Just watched it back one more time and that's exactly it. Was hard to see due to the camera angle cuts in real time.
I now remember seeing it on the WR laws site, under Law Application Guidelines:

[LAWS]The ball can be moved backwards hand-to-hand once the maul has formed. A player is not allowed to move/slide backwards in the maul when the player is in possession of the ball and the ripper needs to stay in contact with the jumper until they have transferred the ball.
Sanction: Penalty kick[/LAWS]
Link: https://laws.worldrugby.org/?domain=9&guideline=9