We were watching with recognition - this happened to Ms Marco 3 weeks ago in a women's Prem match. She was flummoxed by an oppo flanker (ironically, part of the England setup) standing between her and the 10, repeatedly shouting 'tackle only, Sir!' from a couple of metres away.
As I understand it, from that position the flanker is not allowed to tackle the player playing the ball from the previous tackle, to do that she would have to come from behind the back foot of the tackle (over to ElyDave for clarification), but she can stand where she likes on the pitch. I think the tackled player or the next player in is in the best position to play the ball and run straight, which England got the hang of eventually...
Looking at the weekend's game, I don't think any Italian player would be in a ruck if they just had a hand on an England shoulder next to the tackle, but if they go in to try and ruck the ball against English competition and come out again, I think a ruck was formed, whether they stay in it or not (their choice). I don't see a problem with the tactic, but I concede that the first half was one for the IRB law nerds (like me, who found it fascinating). I know the refs try and make the game flow by calling 'tackle only', 'ruck', etc. but I wonder what would happen if they didn't, and make the players think about it a bit more? Would it just be stilted?