‘I didn’t think this song would get as far as it did,” says Maren Morris of the single Rich, which is in the Top 10 of America’s country chart this week. “Because you’re a woman?” asks a fan, pressed up against the stage of this railway-arch venue. “Because I’m a woman,” Morris concurs. “And because we had to take ‘shit’ out.”

The Nashville establishment may find sweary women a trial, yet Rich – a break-up song whose rap-minded lyric references Diddy and Benjamins – is a big hit, and Texas-born Morris one of country music’s most feted young singer-songwriters. Tonight’s acoustic one-off, hastily arranged simply because she fancied it, sold out in one minute. (A large-venue 2019 tour is penned in, along with the follow-up to debut album Hero.) The fuss stems from her gift for pairing storytelling (often told from the “ugly” point of view – “being the bad guy,” as she says of the swampy I Wish I Was) with walloping melodic hooks that cross genre lines to pop and R&B. Even presented as bare-bones traceries, her songs, like her voice, are luminous and characterful; in the case of her inescapable, Zedd-produced EDM hit The Middle, the acoustic treatment replaces its polar chill with warmth.

Tiny and personable, she calls her new husband Ryan Hurd on stage and tackles a potentially mushy duet with the observation: “This is straight-up country shit.” A tribute to the victims of the Route 91 Harvest festival shooting in 2017 – she had played the day before – is elegant: moving yet free of sentimentality. “This gig makes me miss being a songwriter with a guitar,” she says at the end, facing a future where such gigs will be a rarity.