Rugby union is not renowned as a perfect science but the symmetry of this month’s north v south contests has been striking. Four tours by Ireland, England, Wales and Scotland, four narrow 2-1 outcomes, six Test wins apiece for each hemisphere and a collective points aggregate of 280 v 282. The margins across global rugby have never been tighter.

Any one of half a dozen teams, as things stand, could win next year’s World Cup in France and the world’s No 1 ranked team is currently not South Africa, New Zealand or even France. Step forward Ireland, now officially first among equals following the epic weekend deeds of Andy Farrell’s squad in Wellington.

If this month’s most far-reaching rugby result arguably occurred seven and a half thousand miles away in Colorado, where a red-hot Chile have just gatecrashed England’s group at the World Cup at the expense of the United States, there is no minimising the ripple effect of the All Blacks’ implosion on home turf over the past couple of weeks.

It was not just that Ireland were such deserved history makers. If Ian Foster survives the fallout from his side’s alarmingly disjointed performances in the second and third Tests – he missed the first with Covid – it will further thicken the fog into which the Kiwi game is suddenly disappearing, even allowing for the brilliance and defiance of Tadhg Beirne, Peter O’Mahony, Josh van der Flier and Johnny Sexton.

To watch Robbie Henshaw stroll through a bunch of black-clad statues for the try that helped put Ireland 22-3 up before half-time in the “Cake Tin” was to wonder what is afflicting a team who used to set such impossibly high standards. And then to conclude that their aura has been slipping for a while: this was the All Blacks’ fourth defeat in their last five Tests.

No one in their right minds ever writes off New Zealand as a proud rugby nation but Foster – or more likely his successor – must come to terms with some increasingly stark realities. Ireland’s maul, breakdown and, for the most part, lineout were all superior and their midfield offered more power and wit. Every other leading side in the world, not least the Springboks, who host New Zealand next month, will have taken suitable note.

And what does it all mean for next year’s World Cup quarter-finals? Crazily – and in future World Rugby really do need to delay the process to avoid any repetition – the All Blacks, Ireland, South Africa and France are all in the same half of the draw and only two can make the semi-finals. Could it be that neither the defending champions nor New Zealand will advance to the last four? On the evidence of this calendar year so far, it is an increasingly plausible scenario.

Which is why England’s 2-1 win over Australia, even if it was scruffy in places, could prove psychologically valuable. The two sides may yet meet in the last eight in Marseille, just as they did in the same city in 2007, and Eddie Jones could not entirely disguise a wolfish grin when the prospect was brought up following Saturday’s flawed but gutsy 21-17 victory at the Sydney Cricket Ground.

Eddie Jones smiles duirng England’s match against Australia in Sydney
Eddie Jones enjoys England’s match against Australia in Sydney. Photograph: James Gourley/AAP

That is not to say the Wallabies will not be a better side this time next year, particularly if they can beef up their pack with a Will Skelton or a Rory Arnold and stay clear of the injuries which undermined them here. But England, while still a work in progress, have taken a step forward in terms of the coolness of their leadership under pressure and, in Jack van Poortvliet and Henry Arundell, in particular, have unearthed two genuine finds who can make a difference in both the shorter and longer term.

If some obvious issues remain – attacking fluency, the frown-inducing Rubik’s Cube that is the Marcus Smith-Owen Farrell creative partnership, world-class dynamism and more pace – the series outcome has also given Jones a little more breathing space. “I am really pleased with the development of the team,” confirmed the head coach, enthused by the visible progress being made by, among others, the likes of Ellis Genge, Freddie Steward and Tommy Freeman.

Whether he could have stuck to that “performance over results” script following a 3-0 series defeat, which less profligate opponents than the Wallabies might have inflicted, is irrelevant now but what is clear is that no one can currently afford to stand still. South Africa may have won the last Test to clinch the series against Wales but to some degree it will be the visitors who derive the most satisfaction from this month’s three games.

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They can now head for their deckchairs safe in the knowledge the outstanding Tommy Reffell has added further to their excellent stock of back-row forwards, with the outlook under Wayne Pivac now brighter. There is still a heap of rugby to be played before the World Cup and the visits of both New Zealand and England to the Principality Stadium next season can be attacked with particular relish.

Scotland, in the same World Cup group as South Africa and Ireland, have been left with rather more to prove, having allowed a 15-point lead slip and been pipped 34-31 by Argentina in Saturday’s decider. Their frustrating inconsistency is a habit they seem no closer to eradicating and time is not on their side. Simply treading water between now and the 2023 World Cup will not be enough.