Billy Bragg and Joe Henry @ Summerhall, 15 Aug

When Tory premiership, austerity and xenophobia are the order of the day, artists like Billy Bragg have never been more relevant, or indeed, needed. The leftie legend has been playing everything from picket fences to concert halls for decades, always managing to capture the disenchantment and solidarity of Britain’s left flank.

Tonight sees him take to the stage in the old Dissection Room of the former veterinary hospital of Summerhall. He brings with him US singer-songwriter and pal Joe Henry to pay homage to that very American niche genre – the railroad song. The two have just returned from a mammoth train journey between Chicago and LA, absorbing and recording the classics of the late 19th century 'hobo' era into a forthcoming album.

This is the first date on their Shine a Light tour, and the audience in the sold-out surgical hall is largely middle-aged, no doubt fans of Bragg’s for some time. The pair receive the warmest of receptions, and proceed with a set that seems refreshingly relaxed in comparison to the intense choke-hold the Fringe has over the rest of the frenzied city.

It's a set of beautifully simplistic covers from the likes of Leadbelly, Hank Williams and Lonnie Donegan, interspersed with anecdotes of the duo’s Kerouacian travel westward. The talking is mainly left to Bragg, who reminisces about recording in empty cathedral-sized stations, long since forgotten by regular American travellers in the wake of trans-continental flight and mass car production. The stories are often just as interesting as the songs themselves; largely the work of old railroad labourers crossing the US in search of employment.

Although not the sort of musical style one immediately associates with the famously political singer, as he jokingly points out, he considers himself “genre-fluid”. Not so fluid is his worldview, hints of which he makes known. While the audience laughs at Henry's jokes about Donald Trump’s proposed Mexican wall, Bragg reminds us of our not-too-dissimilar position in Brexit Britain. The pair pay particular tribute, through their own version of John Henry Was a Steel Driving Man, to the thousands of men whose blood and sweat built the American railroads, before closing the set with a foot-stomping rendition of Midnight Special.

While a significant portion of the audience probably came to hear some Bragg classics, the confidence and chemistry of the onstage pair means that it doesn’t matter that they abstain from their original material. Instead they play classics of a different kind, shining a light on a culture which is unlikely to be given a voice elsewhere in the world’s largest arts festival.