After the expensive relegation, the lucrative promotion. Southampton contrived to finish bottom of the Premier League in a year when they spent some £160m, had three managers and only mustered six wins. They return to the world’s richest league courtesy of the world’s richest game, their prize for play-off victory probably beginning at £140m and, if they stay up, worth rather more. If Bobby Stokes, the hero of the 1976 FA Cup final, still has the most famous Wembley winner in Southampton’s history, Adam Armstrong has the most lucrative. For Leeds, consigned to another season in the Championship, it ranks as the most costly.

A sixth unsuccessful play-off campaign means they are still without a win at Wembley since 1992. On the 35th anniversary of Don Revie’s death, the Damned United remain incapable of escaping their past. There was another kind of unwanted sequel: a third defeat to Southampton this season, with Armstrong scoring in all three. There were times when Leeds looked like the finest team in the Championship but that trio of losses to Southampton means that, unlike Saints and Leicester, they have not rebounded to the top flight.

In the dugouts, the subplot started in Norfolk in 2017. For Russell Martin, the Norwich captain bombed out to train with the Under-23s seven years ago, it was revenge on Daniel Farke, the manager who exiled him. Martin has reinvented himself as a coach and this was his first promotion in charge. Indeed, there was a danger his reign would descend into disaster when the Saints lost four consecutive games in September. A win over Farke’s Leeds was the catalyst for a 25-game unbeaten run. Now, another has made him a Premier League manager.

Martin had earned points for style in his managerial career but with questions about the substance of his teams. A first year at Southampton has ended with an answer in the affirmative. That he was chosen by Jason Wilcox, the director of football who later decamped to Manchester United, means the Old Trafford newcomer left a legacy.

Wilcox was not there to see it; neither was Southampton’s most infamous fan, Rishi Sunak, who, with his usual sense of timing, had turned up to witness relegation. But Adam Lallana and Matt Le Tissier were sat side by side, stars of Southampton’s last two stays in the top flight. As they lasted 11 and 27 years respectively, there will be the hope Saints prove more than just a yo-yo club.

But perhaps they benefited from one of the bracket of players who are too good for the Championship and not quite good enough for the Premier League. If so, Southampton could be doubly grateful for Armstrong. His last two seasons at this level have produced 52 goals but whereas higher-ranking clubs came calling for Romeo Lavia, James Ward-Prowse and Tino Livramento last summer, they left him at St Mary’s.

In a Wembley fixture with a habit of ending 1-0, the opening goal carried still greater importance. Armstrong got it. His movement has always been his greatest asset. He ghosted in behind Ethan Ampadu to meet Will Smallbone’s pass and drill a shot past Illan Meslier. For Smallbone, a lifelong Southampton fan and the man Martin first turned to in replacing Lavia in his midfield, it was a wonderful moment; for Armstrong, made more potent by the drop in division, a 24th goal of the season to accompany his 13 assists.

His has been an extraordinary campaign. It almost got better still on the stroke of half time: the elusive striker had a shot on the turn saved by Meslier. But if Southampton had more incision in the first half, they could have been made to rue substitute Samuel Edozie’s second-half miss.

Leeds were undistinguished before the break, lacking the spark they demonstrated in demolishing Norwich in the semi-finals. Farke required a response and got one, his side penning Southampton in, Joe Rodon adding another dimension by running the ball out from the back. Crysencio Summerville, the Championship’s player of the year, was subdued by Kyle Walker-Peters to such an extent that he was substituted but a replacement was inches from an equaliser.

Dan James rattled the bar with a half-volley. It was James, too, who drew an injury-time save from Alex McCarthy: the goalkeeper, only playing because of Gavin Bazunu’s season-ending injury, commanded his box in what may prove his last game for the club. It is probably Che Adams’s last, too, with the forward also out of contract. If so, each can leave confident he played his part in restoring top-flight football to Hampshire.

For Taylor Harwood-Bellis, the best of the Saints defence, promotion means the loanee will be bought. Walker-Peters should stay now. Martin faces the dilemma of how many of this side are equipped for the top flight, of what to do with the arrivals in the misguided 2022-23 spending spree, some of whom have been loaned out this season. His policy of playing out from the back, which risked danger against Leeds, could prove still more perilous in the Premier League.

But Southampton will be there. Fourth for much of the season, they took the third spot to go up, their huge overhaul last summer eventually resulting in a change of division.

For Sport Republic, the owners whose maiden year was disastrous, the second has been redemptive. But for Leeds, Wembley had a cruelty, the play-offs a brutality. Again.