Leader, field marshal, setter of standards – Johnny Sexton delivers one final Six Nations Saturday for the ages

When he limped out on 74 minutes with the game won – though his competitive fire ensured that even then he raged and shook his head – the Aviva swooned and curtsied before its timeless and beloved monarch.

It wouldn’t be long before frustration turned to elation and the King of Lansdowne Road - “Ireland’s best ever player,” according to Jamie Heaslip – offered triumphant smiles and pummelled the air in response to the devotion.

As the final seconds ticked down, he patrolled the sideline and surrendered to the moment, a leviathan of the game close to tears, pulsing with fulfilment.

“You couldn’t make it up. Honestly you couldn’t make it up. It’s like living in a dream. I’m actually worried I’m going to wake up in the morning,” he beamed.

“We didn’t play our best, but bloody hell what a team. What a team.

For the longest time Johnny has been Irish rugby’s master switch, its skeleton key, the player who can illuminate every room in the house with a single flourish, open any closed door.

Here he was central to extinguishing an unexpected English wildfire, one that, for a nerve-shattering hour, threatened to consume Ireland and reduce their big night to cinders.

This was not the end, not when the World Cup remains the alpha and omega of the closing chapters of his story in green, but it felt like the terminus of a part of the Sexton story.

And the cartographer of the Dubliner’s life had mapped out something fittingly seismic for his farewell: A Grand Slam secured in his home city, a nation palpitating and euphoric.

A night overloaded with emotion, one that brought a tear to the eyes of hard and grizzled old warriors.

There was a hugely anxious first 60 minutes when, at times, Ireland seemed paralysed by the scale of the prize on offer.

Inevitably, it was their veteran conductor of the orchestra, who guided them to a note-perfect finale.

A pinpoint kick into the corner just after the hour forced a five-metre scrum, seconds later Robbie Henshaw was accepting Bundee Aki’s soft-hands pass and tumbling over.

Sexton converted, Dan Sheehan added his second try of the night (Rob Herring would bag a fourth) and a nervy contest was transformed into a rapturous coronation.

For the second time in a manner of days, just 100 hours after Honeysuckle and Rachael Blackmore galloped up the Cheltenham hill as if guided from the heavens by Jack de Bromhead, a sporting occasion had carried us to the stars.

A celebration, a wrapping of Sexton in love, that warmed the audience with the fire of pure being.

The writer Don DeLillo is not a known rugby aficionado, but a line from the American resonated in the floodtide of emotion.

“Sometimes I see something so moving I know I’m not supposed to linger. See it and leave. If you stay too long, you wear out the wordless shock. Love it and trust it and leave.”

And yet, a howitzer shell could have dropped on the Aviva and still nobody would have been inclined to leave.

Some 50,000 supporters understood that they might never know such an occasion again.

What can be described as a wild deluge of human music – a chorus of uncontainable exhilaration, a deranged outpouring of joy, a oneness of being - flooded the arena.

A high–voltage charge of electricity sparked in the Dublin air.

The fizz of being in the vicinity of history combined with a hunger to salute to an all-time great.

Sexton is not alone in facing the dusk (Cian Healy and Peter O’Mahony understand the hourglass is emptying), but a generational talent reaching the final bend on the Six Nations road added another layer of tumult to the occasion.

Spiky, combative, railing with unceasing fury against both time and any slippage in his or his compadres’ standards, the out-half remains a grandmaster of the playmaking art.

Irish rugby’s irreplaceable listed building, yet still its most voguish, vital landmark.

Leader, competitor, field-marshal, setter of standards.

The commendations from his former team-mates spoke of the cavernous space he will leave at the heart of Irish rugby when he abdicates this autumn.

Rob Kearney distilled it down to its essence: “He is so much more to this team that just a player. Without this on me person the golden generation of the last 15 years would not have achieved all it has.”

Shane Horgan talked of “what’s he contributed to Irish rugby and Irish life – a decade of consistent winning.”

The first half – at least until Sheehan burst through the English cover as if fired from a cannon for a mood-altering Irish try – had been horribly tense.

The occasion seemed to weigh on Ireland, the imperious free-flowing team of recent weeks guilty of uncharacteristic handling errors.

England, unrecognisable from the rabble that succumbed to a Twickenham humiliation at France’s hand a week earlier eased into a six-point lead.

The crowd were desperate for something to cheer, Sexton’s record-breaking 560th Six Nations point greeted with a standing ovation.

But still the customary Irish slickness was proving elusive, the error-count rising.

Then came Sexton’s kick to the corner, a decisive Irish surge and the tension evaporated.

The highly-strung crowd could at last exhale and, even on one leg, Sexton was bouncing along to Gala’s “Freed From Desire.”

On a Saturday for the ages, the keys to the kingdom were jangling once again in the pocket of Ireland’s timeless prince.