Florence isn’t real. Yes, we can see her standing there; we can hear her high-class voice, we’ve been told about her childhood years at an exclusive Swiss school. But it’s all a lie – invented, so she says, in a flash of recklessness born of despair. For “Florence” has a specific ambition, to work in the world of fine art… and if you want to break into that field, you need the right connections.

Playing Florence, Honor Santa Barnes flips in an instant between the Irish tones of her true persona, and the nicely-judged placeless accent adopted by her invented self. The script is quick-witted and agile, filled with amusing pastiches of hedge-fund managers and minor royals, all performed dynamically on a simple stage. As we chart Florence’s progress through an almost surreal world of high stakes and privilege, we also learn about the chicanery of the global art market – and how her employers are playing some shady tricks of their own.

The moral dilemma this poses is interesting, and clever. The lie Florence told should be irrelevant; she’s genuinely qualified for the job, and it’s clear she does a good job, climbing up the ladder through hard work and skill. So does the deceit matter? Might we even applaud the daring way she plays the game? Don’t be too quick to answer, because the twists and turns of Barnes’s plot will challenge any hasty view.

And once you’ve lived someone else’s life, it turns out, it’s difficult to go back to your own. After a while, the now-snobbish Florence begins to surface unbidden, in the style of Jekyll and Hyde – again posing interesting questions about whether ugly entitlement is programmed from childhood, or can be acquired later on. And there’s more to come, another clever twist or two, as Florence tells us more about the formative experiences that led her to the crucial lie.

All of us have sometimes faked it a bit, to fit in a place we didn’t quite belong. In pushing that common pattern to a disturbing extreme, Florence asks when re-invention becomes deception – and does it in a world peopled by vibrant characters, each one brought compellingly to life. Alternately comic and thought-provoking, it’s the genuine article of a play.