Sophie and Simon are sharing an awkward dinner, after meeting on an internet dating site. She’s only left her hometown three times in her life; he’s a moneyed high-flyer. She’s into reading and theatre, while he “thinks Jane Austen is a superstore”. The date’s heading nowhere… until there’s a mishap with a flying champagne cork, and then suddenly it’s heading to A&E.

Original musical First Aid is above all defined by the quality of its lyrics. There’s a cheeky, chirpy audacity to the phrasing and the rhymes; the opening number improbably links medical terminology to the language of love, while a later ditty somehow works an entire rhyming Nando’s order into the middle of a meaningful song. The clever witticisms keep on coming from beginning to end, and every new number crackles with the potential for an unexpected twist or theme.

Both leads do full justice to Barnaby O’Brien’s words. Playing Sophie, Thaejus Ilango combines bright-eyed hope with a cynicism born of experience, while Elliot Wood, as Simon, successfully captures the inner vulnerability beneath the finance-bro façade. Simon’s not the most instantly likeable of characters – but he is, at least, decent enough not to leave Sophie on her own in A&E.

Alongside the romantic storyline runs a parallel story of sibling rivalry, which reaches its height in an affecting duet that will speak to anyone who’s ever fallen out with someone who mattered to them. And the most overtly comic character, the newly-qualified doctor played by Iona Blair, delivers a hilariously pointed riposte to medial “experts” on Reddit, while also having a serviceable character arc of her own.

Underpinning the lyrics are a nice variety of musical styles – some rock’n’roll, some hip-hop, some jazz – all accompanied live on stage by a scrubs-clad O’Brien, who’s also a skilful keyboard player. Not all the singers have the broadest range and a few songs songs did expose that weakness, but the harmonies are beautiful and the energy is high.

There was one moment when I lost my way – thinking we’d jumped ahead a few years, when in fact we were still in A&E – but to be honest, telling a complex story was never the point of this show. It’s funny, tuneful and ultimately heartwarming, and that’s all it needs to be. “Don’t leave a bad review,” exhorts the closing song. I wouldn’t dream of it.