How else could it possibly have gone? Arsenal's recent years have been a tale of frustrations, disappointments and love-sickness but last night they were reunited with their king and their script.

Arsène Wenger said afterwards that it was a story "you would tell some young kids who you wanted to tell a story about football". That used to be how almost everything was at Arsenal: winning the league at Old Trafford, an unbeaten season, winning the league at White Hart Lane, securing Champions League football on the last day at Highbury.

But, since the move to the Emirates, there have been five and a half thwarted seasons. Until last night, when a fantasy was finally realised again.

With 12 minutes left Thierry Henry, Arsenal's greatest ever player, received the ball from Alex Song. In that channel, that inside-left channel, from where he hunted so many of his first 226 Arsenal goals. With a twist of the hips, he opened his body, opened his right boot, and struck the ball into the far corner.

It prompted the most ecstatic celebration the Emirates has seen, certainly since the defeat of Barcelona last year. Henry himself, the consummate actor, reacted perfectly: beating the badge on his chest, embracing Wenger, doing everything possible to demonstrate that he means what he says about love.

The most magical Arsenal moment since Henry's 2007 departure, perhaps, and one that, on this special night at the Emirates, could only have been delivered by one man. This was less a cup tie than a plot device for a restoration, a scene written into the script for just one reason, a necessary mechanism for the re-crowning of Arsenal's king.

The fans might not share Wenger's placing of the cup so far down Arsenal's priority list, but last night they were, for an hour at least, less than desperate about the battle to earn a fourth-round home tie with Aston Villa.

The first thrilled roar of the evening came when the stadium announcer confirmed Henry's presence in the wings. From then on, it was a case merely of passing time before the main event. Around 68 minutes of football relegated to the status of undercard, of preamble, of patient, polite throat-clearing.

When he did ascend from the bench, to replace Marouane Chamakh, the massed devotion was astonishing. For the 10 minutes before his goal, it was a notable high-point in the history of noise in this ground. After then, though, it was obviously and utterly dwarfed.

There was a moment in the first half when it felt as if the plot might be short-circuited. Francis Coquelin, galloping down the right, pulled up holding his hamstring and went down: unable to continue, and requiring replacement.

The whole stadium turned to the bench and when 18-year-old right-back Nico Yennaris was the player clambering out of his tracksuit, there were nearly 60,000 disappointed sighs.

Leeds United, certainly, started the game like a team with Henry on its mind. And not just 2012's 34-year-old New York Red Bull but the 2004 model, the sports car forward who scored seven times past Leeds in the season when he became an Invincible.

Four of those goals came in a 5-0 win at Highbury nearly eight years ago, his last match against Yorkshire's proudest. Simon Grayson's back line defended so deeply they can only have imagined Henry, in his most fearsome form, was running at them. It took nearly half an hour for Leeds to realise they were seeing ghosts, and to push higher up.

But they, like their opponents, were merely playing out time. And like any actors, they were powerless to change the script.