2011-12 saw the Melbourne born prop make a real breakthrough as he established himself as first choice for the Gloucester Rugby number three shirt in his third season at Kingsholm.
And his elevation to the full England squad is an appropriate tribute to the expert scrummaging advice handed out by John Brain insists Carl Hogg.
Three years ago Melbourne-born Harden was plying his trade with North East club side Tynedale in National League One.
Two impressive showings against Cinderford alerted Gloucester to his raw potential, via Kingsholm favourites Andy Deacon and Mark Cornwell.
And the Cherry and Whites moved quickly to snap up the former Newcastle Falcons academy man.
This season Harden forced his way into the England Saxons squad, and now he has his big chance with Stuart Lancaster's full test group.
Hogg hailed Harden's determined development - particularly in the last 18 months - and admitted Brain played a pivotal part in that.
Gloucester's 51-year-old rugby operations manager died last Sunday having returned to Gloucester as a scout in December 2010 but quickly shouldering the two big responsibilities of scrum coaching and rugby operations.
Hogg believes Brain had a crucial impact on Gloucester's developing front-rowers, Cumbria and London-raised Harden included.
Hailing Harden's sheer hard graft too, for hauling himself into not just the Premiership but also the England picture, Hogg backed the former Rugby School pupil to impress on the Springboks tour.
"Everyone at Gloucester is delighted that Rupert has this opportunity, it's a fitting tribute to John Brain's work and recognition that his expertise and acumen has rubbed off on the players here.
"It shows that John has guided the players massively in the right direction, and that imparting of knowledge has paid huge dividend.
"In the last three years but especially the last 18 months, since last Christmas really, Rupert has really knuckled down and set himself some big targets.
"He has gone about his business in a very diligent and professional manner, and this is great reward for all of that.
"He has a great chance to show what he can do now, and it's another stepping stone and certainly a move in the right direction of course.
"It will be a huge learning curve for him out there in South Africa, but he has come a long way in a relatively short space of time, so it will be exciting to see him continue in the same vein."
Confrontational to the last, the South Africans view scrummaging and forward play as almost a way of life.
Former Scotland back-rower Hogg anticipates a huge challenge ahead for Harden, but also expects the Cherry and Whites front-rower to reap big Kingsholm rewards from the experience.
"South Africa has a huge culture of scrummaging and forward play, and it's going to be a huge challenge for Rupert.
"But it's massively exciting as well and I expect him to relish the whole experience.
"International rugby hopefully benefits twofold, in that the player fulfils a personal and lifelong ambition, but they also improve too.
"So it's great from their personal perspective, but hopefully it's something the club can really benefit from too.
"I would certainly expect that this will improve Rupert as a player for Gloucester in the long-run."
Quotes courtesy of Gloucester Citizen