You could quite easily take Johnny Sexton's post-match quotes a step further.

It wasn't against England and in fairness it was more like two-and-a-half years ago, but if an Irish fan closed their eyes at the moment Marcus Smith kicked his fifth penalty they could easily have found themselves transported some 6,000 miles to Shizuoka.

Ireland were heavy favourites going into their second 2019 World Cup group match. They started well, with 12 unanswered points seemingly putting them on course for a routine win.

However, Japan, buoyed by an atmosphere that only a very rare, heroic home performance can produce, chipped away. They won the battle up front and nibbled into the deficit with accurate place kicking.

By the hour mark the hosts had the momentum and the win was there for them. The crowd sensed it, and added to it.

Ireland were by that point destined for failure. Doomed to compound their own misery with a series of basic errors only ever produced with such regularity when a team has permanently and fatally lost its composure.

Amid the febrile atmosphere at Twickenham made possible by the brilliance of England's 14 men, Ireland found themselves faced with an almost identical situation on Saturday.

But this time they found a way to win.

There was no magical tactical switch that saw them wrestle back control, only composure and a steadfast belief that they had the tools to weather the storm and finish the game on their terms.

That was always a distinct possibility against a depleted side out on their feet after such an effort, but it still required Ireland to silence the crowd and drain England of the coursing adrenaline that had up to that point prevented the lactic acid in their muscles from making its presence felt.

After the game Ellis Genge took to Twitter to note that although usually not pleased by the 'brave losers' tag, he was on this occasion willing to make an exception. Quite right, too. Genge was one of several England players to deliver a performance of quite preposterous brilliance.

The hosts threw the kitchen sink at their opponents. They made mincemeat of Ireland at scrum-time, chased every kick like their life depended on it and put in a monstrous effort at the breakdown.

And yet they never came particularly close to scoring a try.

Ireland were guilty of conceding too many penalties and their scrum was calamitous, but their defence held firm and the work of their back three under constant duress was as good as you will ever see.

Amid a highly entertaining and free-flowing autumn series clean sweep during which they scored tries for fun, Andy Farrell was at pains to heap praise on his side's defence. Going forward, it would be Ireland's defence that would dictate how far they could go.

That concept, which will have been drilled into players in the two-year timeframe referenced by Sexton, came to the fore at Twickenham and withstood pressure well enough to ensure that even when the set-piece was malfunctioning they had a response to English momentum.

As for the back three, they vindicated Farrell's selection in an area that is enjoying competition for places to an extent not seen for some time.

It speaks volumes of his performances that despite the deserved hype surrounding Michael Lowry and his two-try debut last time out against Italy, Hugo Keenan's return to the side was never in question.

From obscurity the Leinster man made a meteoric rise to nailed on starter by the end of 2020, and his reputation will only continue to skyrocket after he came up with an answer for every question asked of him at Twickenham while finding the time to pose several of his own.

Andrew Conway's nerveless 50:22 kicks should have been the precise moments when Ireland flipped the momentum were it not for more set-piece woes, while James Lowe is now proving himself to be everything Ireland had hoped when he became eligible in 2020.

The point is; since their upturn in form midway through the 2021 Six Nations, Ireland's mettle had not been tested like it was on Saturday.

The All Blacks in November and France in Paris last month were far from free hits, but Ireland went into both as underdogs and defeats would, provided they were not suffered emphatically, not be seen to have thrown the team's progress wildly off course.

With 20 minutes to go at Twickenham it appeared likelier than not that Ireland would crash to a defeat in a game they had no right to lose.

That they pulled away from a 14-man team late in the contest was not a surprise nor a massive achievement.

The big takeaway was the way in which, despite all the imperfections and violently flashing warning signs, they found a way to compose themselves and do what needed to be done.

Sexton was right: the significance of the win came from the fact that it was not one they would have managed two years ago.