Oh well. All the best south London parties last three minutes. Everyone knows that.

Bermondsey had been a spring-like place at kick-off, soft May sunlight dappling the magnificent municipal incinerator tower at the Cold Blow Lane end. The Den was sold out, as it always is these days.

And the job for Millwall was clear enough. The playoff spot was guaranteed. You’re going home with that. But a better result at home to Oxford than Ipswich at home to QPR would mean Millwall could gain promotion to the Premier League before the day was out, to the top tier for the first time in 36 years, and basically get to paint south London blue for the next three months.

The ground was up before kick-off, the air crackling with that very distinct electricity. The usual playlist echoed around the corrugated stands. Let ’em come. No one likes us. Your dad’s a nonce. We fear no foe – except, it turns out, for news of an Ipswich goal after three minutes against a QPR team already playing in sliders and pieces of snorkel equipment.

The moment passed with just a flicker around the ground. The sun kept shining. The trains kept trundling past the empty corners of the stands. Alex Neil’s face appeared in Stalinist close up, a grimace on the big screen. This is the beauty of sport: 87 minutes still to run. Play on, play on. Smile when your heart is breaking.

With nine minutes gone it was 2-0 to the Tractor Boys, as instantly relayed by the Oxford fans in the away end, and the suspension of disbelief was finally banished for good. “You’re going down,” the Dockers stand replied. Before long we were into the anti-Keir Starmer repertoire and the day had begun to settle.

This was always a strangely pitched occasion. There is a giddiness to getting this close to an automatic spot, a sense of tantalising proximity to be managed. For the players, particularly at Millwall, which is almost exclusively EFL old hands, going up would be a career changer, a one-off shot.

Neil had been agreeably dour and low-fi in the buildup, with lots of stuff about nothing we can do about results elsewhere, and not spending the day listening to his transistor radio (classic, old school). Afterwards, with Millwall confirmed as third-place finishers, his only comment was “well, I’d have preferred second,” followed by praise for his team, and the freedom with which they have played under pressure in the last few weeks.

The real job here was simply to keep that train moving, the energy up, the vibe good. And Millwall did just that. Femi Azeez was brilliant, a man having fun in the sun, too much for the Oxford right side, and scorer of both goals in Millwall’s 2-0 win.

With 55 minutes gone Azeez even reeled off a blocked Rabona cross, and people laughed and shouted approval, rather than ripping up their season tickets in disgust. It’s all changed around here. You can buy artisan pickle on the Old Kent Road.

For a while early on it was probably good nothing was really riding on the result, as Millwall kept finding endless ways not to score, crosses fizzed across the six-yard box, shots wumped into the nearest desperate block.

Oxford were decked out in an eye-watering bright teal, the kind of colour your local bathroom supplier would call Spearmint Bidet. They hung on as Millwall ticked off a series of corners, Jake Cooper a reliably massive target, wheeled into place like a medieval siege tower for every set piece.

Barry Bannon was the best player on the pitch, always somehow ambling into the right spot. And on 33 minutes Millwall finally scored. It was a lovely goal from Azeez, a shift of feet and a shimmy, the ball spanked powerfully into the roof of the net. He made it 2-0 just after half-time, finishing nicely at the far post.

Either side, Millwall were as good as they could have hoped to be, in an empty game against demotivated and frankly not very good opponents. And from that point there was time to wonder about what next.

Something has shifted around the idea of Millwall going up. There was an assumption for a while that broadcasters and administrators Just Didn’t Want It, for whatever reason. They do now. It’s pretty clear. Millwall are on TV every other week. This is after all the content era: noise, heat, eyeballs. The product can, let’s face it, seem a little cold and processed at times.

Well, not around here. Name another Premier League club where a triumphant sunlit final day to a still-active season is going to end, as this one did, with a mass pitch invasion by local 10-year-old herberts, there to offer V-signs and fight intros to the 2,000 away fans, before being shouted off their own pitch by the rest of the home crowd.

So Millwall roll on to the playoffs in two weeks’ time. They will face Hull, who edged out Wrexham, thereby saving us all from the inevitable Hollywood plaything conspiracy theories. Who would the Premier League want on their screens, eh? Deadpool and the other bloke? Or Selhurst Timber and Building Merchants?

Southampton are probably the strongest team in the mix. But Millwall will fancy their chances of reaching Wembley, with a second leg against Hull back here at the Den; and a wider sense of pride at what is already the club’s best season in three decades.