Reflecting on an interview that had been both “fun and awkward”, Buzz’s Carl Marsh recently ventured: “Perhaps that’s the best way to sum up Wet Leg.” On tonight’s evidence, he’s not wrong. Maybe the air of discomfort comes from having swapped California for Cardiff in the last two days, or nerves brought on by the knowledge that the set is being broadcast to 6 Music listeners everywhere on this, the last day of the radio station’s festival in Cardiff – and that some songs (Ur Mum in particular) require Rhian Teasdale to tiptoe through a minefield of unbroadcastable words. Or maybe, as Carl surmised, awkwardness is just their natural state.

The set – supporting Wet Leg and Johnny Marr – opens tentatively but gathers momentum as it progresses, backloaded with the singles that have whipped up anticipation for their imminent debut album. As the awkwardness subsides, the fun comes to the fore. Teasdale and songwriting partner Hester Chambers grin, giggle and twirl in tandem, the former’s caustic tongue and sardonic wit elevating their pocket earworms above the ordinary. While there’s a faint suspicion that attention-grabbing debut release Chaise Longue may become an albatross around their necks, that time certainly hasn’t come yet.

On one view, the festival programmers have taken an admirable gamble in putting Rebecca Lucy Taylor, aka Self Esteem, in the middle of tonight’s bill: a golden opportunity to win over new fans. On another, they’ve thrown her to the boorish, lairy and Johnny Marr-devoted wolves. At one point, early in the hushed, hymnal John Elton, it seems Taylor has been knocked out of her stride by a heckler and chatting twats at the bar – but she stops, smacks down the disrespect and resumes, head held high.

As Chloë Edwards noted when she spoke to Taylor for Buzz in October, Prioritise Pleasure is a bold, utterly unapologetic record preaching empowerment, empathy and self-care. Tonight, the stadium-sized pop hooks of Moody and The 345 bulldoze any resistance; it’s remarkable to think that a performance of this scale/ambition was squeezed into Clwb Ifor Bach barely five months ago. The true showstopper, though, is I Do This All The Time – a song that, like the rest of the album, is about “how complicated it is just to be a human”.

Taylor may be a pop star in the ascendancy, but importantly she’s also human, battling heroically against a voice that’s threatening to give out and fluffing one of the choreographed moves (“Does Rita Ora do this?” she laughs). It’s her relatability – and that of her subject matter (self-doubt, toxic relationships, everyday sexism) – that makes her so engaging.

It’s a shame that Self Esteem’s core demographic then heads for the exits, not returning the courtesy of listening without prejudice to today’s 6 Music Festival headliner, Johnny Marr. Frankly (Mr Shankly), with the notable exception of Spirit Power And Soul – which profitably taps into XTRMNTR-era Primal Scream – Johnny Marr’s solo material proves to be deathly dull dadrock. While a version of Electronic’s Getting Away With It lifts the mood, Get The Message is disappointingly lacklustre. When, after a run of four of his own compositions, he asks “Everyone OK? Are you still with us?”, the answer isn’t unequivocally affirmative. Please, please, please let us get what we want….

Mercifully, he gets the message, and we’re treated to Smiths classics Panic, This Charming Man, There Is A Light That Never Goes Out (touchingly dedicated to “Dave Grohl and the Foos family”) and an encore of Bigmouth Strikes Again and How Soon Is Now? – Marr staking claim to the songs and freeing them from the negative association with that wretched turd Morrissey. Boisterous collective joy ensues.

Rebecca Lucy Taylor has recalled being “in skinny jeans oversinging the fuck out of a Smiths song” when she met former Slow Club bandmate Charles Watson. Not so different from tonight’s crowd, then – and “I am human and I need to be loved” could easily be a Self Esteem lyric. Introducing Johnny Marr to the 6 Music Festival stage, Stuart Maconie notes how his music has changed lives – just as Taylor’s is changing lives now. 

Great Hall, Cardiff University Students Union, Sun 3 Apr

words BEN WOOLHEAD photos TIM ALBAN / SARAH JEYNES / JAMIE SIMMONDS