‘The dancing is very athletic, you don’t get people milling around with drinks and handbags and chatting. You don’t disturb people when they’re doing it, you just let them lock into it.” Elaine Constantine, the photographer turned filmmaker, has been into northern soul since she was 14. Since she’s not yet 50, this makes her an extremely spring chicken in the scene.

On Thursday, Micky P, outside the northern soul night in Wednesfield Conservative club in Wolverhampton, said: “It was different in the 60s to how it was in the 70s.” “Careful,” said his friend. “You’re showing your age.” “I’m not bothered!” he yelled. “My age is the age of soul!”

Constantine’s film, Northern Soul, released this week, was 17 years in the making. Across the country on Friday, cinemas were dragooned into screening it, by people who couldn’t believe it wasn’t on general release. Northern soul all-nighters have started to spring up again, across the north, gathering hundreds of people. And while this signals a revival among young’uns, in a way the more extraordinary thing is that so many people have been into it since the beginning.

“Northern soul was happening everywhere except London,” Constantine says. “That’s because London had a new release culture. They were pushing psychedelia, but a lot of these kids, they didn’t want to wear makeup and dress like hippies. They were coming out of the mod movement, which also played a lot of soul. They had shit jobs where they were dirty in the day – when they went out, they wanted to look sharp.”

Andrew Marlin, 61, was wearing the Fred Perry shirt that he bought in 1970. Between 1971 and 1979, he never missed a Wigan weekend. “I was marked one of the best dancers there,” he says. “Not being big-headed, but I was.” He says his father died at 91 on a dancefloor, but I took this with a pinch of salt.

His dancing was, however, unfakeable (I saw it with my own eyes): inimitable, sparse, solitary, beautiful. I don’t mean beautiful in a sentimental way – what a beautiful life, still to be lost in the music of your youth, on a Thursday night in 2014. I mean it literally: graceful and instinctive, like a deer. They say you’re meant to dance like there’s no one watching; no one said you couldn’t watch. Sarah and Deborah, both 53, drove 40 miles from Kidderminster to Wednesfield. There were many friendships there dating back decades: Terry Bonser and Steve Hill are both 56. “I’ve been married 31 years,” Terry says. “Thursday nights, I go out with Steve. End of. He goes off for a dance, I don’t really, and then he comes back. Sounds funny when you say it.”

“Sometimes at work,” Steve says gruffly, “they’ll say, ‘show us a few moves’, and then they’ll be, like, ‘where did you learn that?’ I didn’t learn it. If the record comes on, you just go.”

Deborah says: “Because you’re a solo dancer, there’s no pressure on you. You don’t have to rely on anybody. You just do your thing.” That partly accounts for the timelessness I think. It’s difficult, if you’re dancing with someone, to be 15 again when they’re 53. Dancing alone, there’s a quality of skittishness in everyone, except the ones with dodgy knees.

There’s talc in the corner of the dancefloor, though the purists don’t like it. “You don’t need talc,” says Marlin. “Just get some leather soles.”

Debbie describes going to the famous Wigan Casino: “We used to put our vodka in a squeezy bag, so if they squeezed your handbag, they couldn’t feel it. One night, we just didn’t get time, and my friend went with a bottle, and they found it, and they confiscated it. They put it on the back shelf, and it was, like talc, talc, talc, talc, bottle of vodka, talc.”

It’s famously, as Constantine says, a non-drinking scene. “There was never no beer,” says Peter. “You could never get a drink at the Catacombs.” I don’t think vodka counts, as in so many hobbies.

Swoz and Les Beaton (who runs the night with his wife, Carol) DJ under a frilly standard lamp, their record collections worth tens of thousands of pounds. “The sad thing is,” says Swoz, handing me 7”in after 7”in records, for me to look at and give back, even though he’d whited over the labels (for confidentiality), so they all looked the same, “when I go, my kids aren’t going to be interested in any of this. They’ll find someone to buy it, but they won’t keep it for themselves.” He hands me a record in an anonymous homemade white cardboard cover, a note on it saying: “RIP Max, not to be sold, ever, never, until we meet.” No, crying? Of course not. Something in my eye.

At Euston station in London waiting for the train to Wolverhampton, I ran into the Wigan MP Lisa Nandy, who was outraged that I was going to the Midlands instead of Wigan Casino. But that whole thing, of northern soul starting in the proper north is a massive misremembering, says Phil Dawes.

“Catacombs was open three years before Casino. They used to try out the records in Wolverhampton, and if they worked, take them to Wigan.” He still goes to all-nighters now. In September, there was one at the Tower in Blackpool. “Nearly 1,000 people. Unfortunately, a guy died. He was only 51. He collapsed at 1am, they had us back on the dancefloor at 2. They said, ‘If it were one of you, would you have wanted it to carry on?’” It went all night.