Called into Joe Schmidt’s Ireland squad to help with preparations prior to the opener against France in Paris, he obviously did well enough to be asked back this week for the short get-together in Dublin.

And, with Chris Farrell joining Robbie Henshaw on the list of midfielders unavailable, the former Ulster man finds himself shuffling up a queue that will likely be headed by Bundee Aki and Garry Ringrose when Scotland visit tomorrow week.

“I want to play for Ireland, that is no secret,” Arnold explained this week. “To be honest, I tried to look ahead a couple of years ago and, by looking too far ahead, it didn’t work out for me with injuries and stuff like that.”

Not just any old injuries. He tore a hamstring three times, did something serious to a posterior cruciate ligament, then a medial ligament and he went and popped a calf muscle just as the current season was kicking in.

Add it all up and he lost 15 months of his career.

Arnold was a starting centre alongside Ringrose with the Irish U20s. Joey Carbery and Jacob Stockdale were teammates, too. That trio have 26 senior caps to their name already but Arnold may have to wait until the summer tour to Australia to join them.

Then again, who knows?

Schmidt was already planning without a British and Irish Lion centre in Jared Payne this season before Ringrose, Henshaw and now Farrell earlier this week in training came unstuck and the head coach clearly has plans for 21-year old Arnold.

The Kiwi spoke this week about the need to educate young players to the ways and means of the Irish playbook and the Surrey-born man with Wexford and Cork roots made reference on Tuesday to the focus on making decisions under fatigue in training.

“Just being in that environment, it takes a while to learn the plays, learn the shape, learn the way that Joe wants us to play. It's a specific way that he wants us to play, just familiarising myself with that environment.”

He was already comfortable in his new Munster shirt before he committed a high tackle on Ulster’s Christian Lealifano in Belfast on New Year’s Day. Cue a three-match ban at a time when his form was consistently impressive.

He used the layoff to good effect, working on his conditioning and allowing the odd knock and niggle let itself out the door but, as luck would have it, Farrell returned from injury himself a week later and took up residence again at outside-centre.

And now the world turns again. For both of them.

Arnold is a different player to Farrell. He is shorter and lighter, most obviously, but he can take heart in the manner in which his clubmate and the likes of Ringrose, Stockdale and Carbery transitioned so smoothly into the Test arena.

“Yeah, that comes to being in the environment for a while. Chrissy came in prior to the Six Nations camp and Joe has kind of crafted him and moulded him. And so has Andy (Farrell). He knows what he has to do when he's out on the pitch.

“It's black and white. Chrissy works incredibly hard as well. He would have known his detail inside out and once you do that it's a matter of going out there and performing as best as you can and just enjoying it well at the same time.”

Arnold and Farrell have benefited from their switches to Limerick this season and the relative lack of upheaval when Johann van Graan succeeded Rassie Eramus at the tip of the coaching pyramid has been a godsend.

Among the threads knitting the two regimes together is Felix Jones, Munster’s back line and attack coach who reportedly turned down an offer to join Erasmus in South Africa as skills coach to the Springboks.

“He has been absolutely incredible. There has not been one training session where Jonesey has not stayed out with me, called me aside and I have asked him to do a bit of kicking, a bit of passing, a bit video analysis. He is always ready to go the extra mile.

“He has been superb in helping the young backs come through in terms of Alex Wootton, Dan Goggin and Darren Sweetnam. He is absolutely awesome and he takes pride in seeing his young backs trying to push on.

“He is an awesome guy to work with, an incredible coach.”