Now that a Home Counties accent, a home studio and parents who can put you through music school is your best route to a music career, it’s invigorating to wallow in a past when that wasn’t the case. Once, kids from the provinces with nothing but anger and disillusionment to their name did just pick up guitars and play their way out of a life on the assembly line or in the dole queue. It was raw. It was messy. But it saved people. To hear Richard Jobson talk of himself in his early days as “feral, quite violent” is to feel the tension and desperation of 1970s Fife (for which read Derry, or Liverpool, or Salford or any other town whose bleakness birthed a strange kind of musical beauty).

Tonight’s Dunfermline double-header is invigorating in another way too. It’s pishing it doon. And not just drizzle, not spitting, a full-on Caledonian monsoon. The Scottish weather is not about to ruin the vibe of Summerhall’s open-air courtyard festival by staying clement. They didn’t call the festival Southern Exposure for nothing.

Best of all, no-one cares. This is cathartic escapism for a certain tribe of blokes (and though there are some women really into it, it is mainly blokes). “I seen these boys in 1979. Fuckin’ brilliant”. It’s that kind of gig. Pure and straight and honest.

It’s all a bit interchangable and incestuous with the personnel in these two bands these days. Big Country take to the stage, but it’s really a Medium-Sized Country, down to half its original members – Bruce Watson on guitar and Mark Brzezicki on drums, with Watson’s son now a second guitarist, Scott Whitley on bass and Simon Hough on vocals.

But the sound… it’s all still there. That Celtic rock that could once fill arenas is utterly unchanged. Watson’s unfairly maligned bagpipe guitar sound rings out loud and clear, piercing the early evening air and the strong-voiced Hough is a near vocal replica of his predecessor. Something appears to go slightly awry in both Look Away and Fields of Fire, almost as if a monitor’s playing up, but not so that it affects the flow much. Ultimately, it’s a parade of unabashed rock anthems – Harvest Home, Wonderland, In A Big Country – with heart-on-sleeve blue collar lyrics like Wonderland‘s “I am an honest man / I need the love of you / I am a working man / I feel the winter too”. A few later favourites are missing – no King of Emotion, no Broken Heart (Thirteen Valleys), no Save Me – but in concentrating on early days, Watson shares a nice story about writing songs across the road from Summerhall before flying out to record what would be the band’s number one album, Steeltown, in Abba’s studio in Stockholm.

All this happy nostalgia, though, will now forever have its sad side. The late Stuart Adamson, the man who unites the two bands, is powerfully felt in his absence and it’s not long into the Skids set before Richard Jobson pays his respects. It’s not announced as a minute’s clapping, but it’s as good as.

Jobson, now living in Berlin with his Italian wife and with a daughter who runs a Shoreditch restaurant, is a man made good and one assumes more an art gallery and sparkling mineral water man than a Tennent’s swilling Fife thug these days. But there is something of the old punk still in him, not least in his patter.

“Leo Sayer is a wanker,” he fruitlessly tries to get us to chant, eventually realising some of this audience are probably partial to the bubble-haired one these days. “Shut yer pus,” he has us shouting at some fella in the crowd who calls out songs too early. Then to emphasise his roots, he too reminisces about coming to Edinburgh to record with only a couple of quid, enough for one song. There’s also quite an un-punk plug for his lyrics book. By illustration, he introduces Working For The Yankee Dollar as more relevant now than then, which is probably true, even if musically its of its time.

No shrinking violet is Jobson – who else would have his band t-shirts printed with an image of his own face? He throws himself round the stage uninhibitedly in a manner you’d slyly admire if done at a wedding party. Onstage, the dad dancing is faintly daft, a fact he acknowledges himself when complaining no-one came to his “dance clinic” when his bandmates were leading guitar and drum workshops recently. But what the hell, he’s enjoying it, as are the rest of them, including the Watsons pulling a double shift.

The rain steps up a gear as if to honour the night’s highlight – the glorious, unfettered The Saints Are Coming. It actually gets up enough to take out the PA in the middle of Masquerade, which Jobson covers for with an impromptu The Band Played Waltzing Matilda. They finish with – what else? – Into The Valley, and its novelty-ish B-side TV Stars, before dashing off somewhere dry before the deluge writes everything off.

It’s not been big or clever, it’s been middle-aged blokes hammering out no frills rock. But there’s still deep joy to be found in it and a reminder that even in its grimness industrial Fife threw up some gems.