Dylan Hartley will kick himself for 'stupid' red card - Sean Cronin
The enduring image from Friday's battle at Franklin's Gardens is of Eddie Jones raising a gloved hand to his face as his England captain trudged off the field, having secured himself another suspension.
The duration of Dylan Hartley's absence from the game has yet to be determined, but there have been calls for life bans in some quarters, given the New Zealand-born hooker's less than illustrious history with disciplinary matters.
He will learn his fate from a disciplinary panel tomorrow.
The reckless swinging-arm connection with Sean O'Brien's head, described euphemistically by Leinster as a "mechanism" is the latest transgression to add to a lengthy rap-sheet.
The Ireland flanker has completed the Head Injury Assessment process and has not been diagnosed with concussion - he can consider himself very lucky that some neck pain is the worst of his problems.
Few get as up close and personal with their opposite numbers than hookers, so Leinster No 2 Sean Cronin is as well-placed as any to discuss the enigmatic figure that is Hartley.
The Northampton man is about to pass the 53-week mark of accumulated bans, yet he remains a central figure in Jones' England revolution and was being touted loudly for the Lions captaincy until his six-minute cameo on Friday night damaged his chances.
"I always thought he was pretty calm and level-headed," Cronin said of a man he has faced several times for province and country.
"When he came on on Friday we managed to get two scrum penalties and I don't know whether that fired him up a small bit. It was obviously rash what he did, stupid.
"He's a class player. England have done so well in Australia and in the autumn series so I'd say there's no-one kicking themselves more than himself this week."
Although he is the apple of Jones' eye, Northampton appear to have fallen out of love with their former captain, who has led England to 13 victories in 2015 while only appearing nine times for his club.
Former England captain Lawrence Dallaglio questioned Hartley's commitment to the Saints before Friday's game as talk of unrest behind the scenes at Franklin's Gardens grows.
"You hear a few noises around the place, there could be something up with the club situation," Cronin said
"I hadn't heard it before, you can look at his form for England he's been playing really well.
"I presume he's going to get a ban, but (last week's starter) Mike Haywood is a top quality hooker and it could galvanise them as well."
Discipline has been a hall-mark of the Irish sides over the last number of weeks and Cronin says it is not too difficult to keep your head when the opposition begins to cross the line.
"It's part and parcel of the game, you have to get on with it," he said. "It's very hard in today's game to get away with stuff, there's camera angles everywhere, you're hoping that's the protection that you need - from them, from the referees and the assistant refs.
"That's the trust we have to have in them, then we go out and focus on playing the game, playing it clean and playing it hard. That's what we do at Leinster, we try and drive discipline.
"It's worked very well for Ireland over the autumn, keeping penalty counts low, teams are winning big games these days from keeping their penalty count low and keeping on the good side of the referee.
"Even when we had the flashpoint on the weekend, it was focus on the next job. It was our penalty, about the lineout, about the process, about what we're going to run after that."