As the shutters roll up on Glasgow’s O2 Academy at precisely 7pm there is a queue bunched along the footpath south, past the bus shelter, 150 meters to the corner of the block, and another 50 metres past the bend. The O2 priority queue runs half the width and the full length of the building in the opposite direction. It is busy! Even the threat of imminent rain hasn’t deterred fans from showing up early to wait it out: that’s a special kind of devotion typically reserved for pop music’s elite and their often youthful audiences. Increasingly though, UK music fans all over the country are coming out in unprecedented volumes for any live music veiled under the “country” banner and it’s unsurprising, given the statistics on streaming and sales of the genre in recent years. Ironically, much of country’s growing popularity here has been attributed to a lack of attention to genre or categorisation by Millennial and Gen Z audiences; that the music is thriving here in spite, rather than because, of being country. There is also something to be said for the genre-fluidity of UK radio and its listeners compared to the US where the scope for discovery is more rigidly limited. Whatever the reasons, Brett Young has sold out his entire UK run of shows this autumn. Having already delivered a headline-worthy performance at Glasgow’s OVO Hydro for C2C back in March, the California-via-Nashville singer songwriter has nothing left to prove to his Scottish fans tonight.

Some pressure, in theory, should sit on the shoulders of the tour’s opening act, Callista Clark, who is first to face Young’s hardcore fanbase each night. If the young Georgia-native is feeling any urgency to impress she doesn’t show it. Her delivery is easygoing as she takes time to introduce herself and each of her songs in turn, by title and theme. The opening lyric “Too old to cry and too young to drive” begins the title track of her debut album Real To Me: The Way I Feel and positions Clark’s youth and vulnerability at the fore of her songwriting. This bluesy lament feels familiar yet fresh with Clark’s surprisingly rich tone resonating cleanly over her acoustic guitar. An R&B influence shines equally bright on songs like Brave Girl and the lilting Sad, the latter of which Clark prefaces as one of her “sassy” country songs. Following this up with Worst Guy Ever, she demonstrates how sweet sincerity and witty wordplay have been foundational to the best songwriting within country, particularly in launching some of the genre’s biggest stars. Her straightforward lyricism and understated emotional delivery cut to the heart, especially in the live setting, and the audience grows increasingly attentive and endeared with each song. Closing her set with the catchy upbeat single It’s ‘Cause I Am ensures both Clark and the audience part in a high spirits.

The transition into Brett Young’s smooth country pop is seamless from here. Love is his lyrical specialism and over the course of 15 radio-friendly songs he dissects this subject – both noun and verb forms – from various angles. His vivid storytelling and affecting voice are an engaging combination; Catch and 1, 2, 3, Mississippi start the set off in heady new-romance territory, all butterflies and dizzying distraction, before the crushing comedowns of Like I Loved You and You Ain’t Here To Kiss Me. The tempo and energy switch up with the lyrical tone but the audience remain elated throughout, happy to sing along at every opportunity. Young is most dynamic when he is free to move about the stage, pointing, smiling, waving and directing his gaze towards fans, but when he takes up acoustic guitar in front of a static microphone he surrenders a degree of that connection. The performance doesn’t suffer for it though; the added instrumentation provides an extra layer of richness and vibrancy while grounding Young’s songs with a simplicity that is irresistible.

Tracks from his latest LP, Weekends Look A Little Different These Days, showcase a natural maturing in Young’s perspective and presentation of romantic relationships, whether he is mining personal experience or not. This and Not Yet muse on the power and potential of growing deeper in love with “your person” while later in the set, an earnest introduction precedes Lady, which is dedicated to Young’s wife and two daughters, his inspirations for writing it. Acknowledging that a lot of his songs are directed at happy couples, having just encouraged slow dancing to the dreamy ballad In Case You Didn’t Know, Young also offers some solace for the broken hearts in the room. Mercy is especially moving as the band is stripped down to just Young on vocals with bandmate Matt Ferranti on keys and the audience forming a boisterous but tender choir. The reception to this is so loud and sustained with applause, cheering and stamping, that Young is forced to pause for more than a minute before delivering the final “…have mercy”.

It’s unclear whether the final three songs are intended as an encore given Young’s periodic absences from the stage throughout the set. Perhaps he’s not well? Feeling homesick? Road-weary? Whatever the reason, the night winds up with You Didn’t, a track seemingly torn straight out of the Boyz II Men songbook, before closing early with a rousing singalong to the chart-topping single Sleep Without You. Despite being tightly packed in from the outset the crowd somehow find space to move and dance around for one final number, maximising every last note as the band plays on even after Young’s departure. Having waited so long, it’s totally understandable.