The Wirral singer is having "a moment of emotional crisis" after suffering a coughing fit during the opening number, an a capella cover of Son House's Grinnin' In Your Face.
Clearly thrown by the incident, she manages to complete a song from her second album, "which I haven't written yet," then flits indecisively from acoustic guitar to keyboard before exiting the stage all together.
Back after a cigarette break with a three-piece backing band, she appears more focused if slightly nervous at the prospect of having to win back the audience.
It's an apprehension that's well founded for, despite the amount of goodwill in the venue, she only manages to give fleeting glances of the assured chanson artist who produced debut album O, Devotion!
The material here seems to take less inspiration from US pre-war folk-blues than from mid-tempo jazz, including an encore of the Andrews Sisters' Bei Mir Bist du Schoen - and the spirit of make do and mend. It's in this spirit that, at one point, she dons a handmade crow's head mask to sing Cock Robin while at another she performs a rather impressive mouth trumpet solo on Bad Medicine.
Yet amid the forgotten lyrics and glances for reassurance to her band, there are moments when everything finally gels.
The Quiet conjures images of a carnivalesque, funereal jazz-march, while solo set-closer Gallows is imbued with extra layers of darkness when Green explains it was inspired by a hangman discovered in the family tree.
These renditions are too late to completely salvage the set but there's no doubting that Green has a talent that she's only just finding the confidence to develop.