Now England know it too. There's nothing bite-sized or ephemeral about Robbie Henshaw. He's inexperienced but not callow, green around the gills but with edge and purpose. Even under Joe Schmidt's brutal gaze, he's not stuttering, he's not wilting.
Stuart Lancaster bemoaned Henshaw. Andy Farrell quietly cursed him. There were some if onlys from the England camp. One of them was if only Henshaw hadn't given the nod to his scrumhalf and fetched a high ball for Ireland's only try.
‘Backed myself’
"I spotted the space in behind Alex Goode because I was up with the line and I just backed myself," said the Irish centre.
“I caught Conor Murray’s eye. We had practiced it a couple of times, where if we did have a penalty advantage we would possibly put in a kick over the top and have someone chase it.
“I just happened to be there and gave the nod to Conor to put it in behind and thankfully got on the end of it. Yeah, I just caught his eye. I didn’t go too mad in case I’d give it away.”
Given the way the end unfolded as England forced Ireland into their own quarter, Henshaw's seven points were far more than a decorative filigree to Sexton's boot. It was the final 20 minutes and their dominating finish, where England looked for comfort after the match.
“I think if we hadn’t gotten a try we would have been under the pump,” admitted Henshaw. “Certainly towards the end, when they got back into our 22 ... they created good opportunities for themselves.
“Luckily enough they threw a forward pass in the corner and we got out of jail there.”
Despite, or maybe because of the imprimatur of Brian O’Driscoll, Henshaw is still learning to talk about himself. The team, his scrumhalf, Paul O’Connell, Johnny Sexton, the pack. Anybody you like, Henshaw will speak about. Just don’t ask him to talk about Henshaw. A game contribution that won him man of the match against a side known for closing space and bringing muscle to the party and he was able to bring his own bespoke biff and blazing runs.
Scuffed and scratched, his face and cheeks still burning red from the countless times he wrestled England players to the ground, was stood on and was smacked, he topped the Irish tackling with Tommy O’Donnell, 13 each.
It's his first try in Aviva, first against England, first in the Six Nations Championship, and after eight caps one that, along with his debut, will be another signpost on his career curve.
“Yeah, I know, I was pretty shocked after it,” he says. “It was a special moment and hopefully tonight I’ll have another look at it again. It was pretty special getting the try at home, and against England as well. Certainly I wasn’t thinking about it when it happened. I was just there and I did the job for the team.”
There was also a near miss in the first half as well but a painful ankle took some fizz from his run. “Yeah, I just got tap-tackled and I had rolled my ankle just before that play so I wasn’t sprinting 100 per cent because it was still sore at that time,” said Henshaw.
Man of the match
First man of the match award for Ireland too. “Yeah,” he says. Well, what more can a 21-year-old add, and he’s becoming adept at finding an escape route from talking about Robbie.
“I think speed to the breakdown and winning the shoulder battle was massive,” he says. “A couple of times England had us clustered in and they had space out wide, and luckily a few of our backrow got on some serious ball.”
“I think England knew what we were going to throw at them and they expected the aerial game to be a big factor of ours.”
Perhaps, and maybe one thing that they didn’t fully expect was the Irish number 12.