The beauty of the piece – and arguably the reason it has proved so popular – is its form. The audience is assigned items from the list to read out during the performance. Some people are even invited to play roles in the story. Over the course of the show, the audience becomes a kind of choir – a temporary community.

It’s a gift of a role for an actor who enjoys thinking on their feet and working with a crowd. Donahoe – one half of musical comedy group Jonny and the Baptists – excels at this. He works with everything the audience gives him, putting everyone at ease while never losing sight of the emotional core of the play.

Having co-created the show with Macmillan, he played the role until 2017, during which time he took it to New York for an Off-Broadway run at the Barrow Street Theatre. Since then, there have been productions of the play all over the world and several revivals in the UK. Last year, to mark the 10-year anniversary, I spoke to several of the actors who have performed it, from Singapore, Greece and Germany. They all agreed that while the text affords its performers a degree of flexibility – it’s possible to tweak the musical references and tailor it for local audiences – the play’s central gesture, of uniting people in a discussion about depression, was the reason it resonated.

A couple of years ago, out of curiosity, I went to see a version of the play in Slovenia. Uroš Fürst, a member of the ensemble at the National Drama Theatre in Ljubljana, was playing the role with a softly spoken, gentle energy that generated a real sense of intimacy in the room. I don’t understand much Slovenian, but I could sense the audience warming up to the idea of participation and feel the emotional beats landing.

Fürst was performing in the National Drama Theatre’s studio space, and I suspect most international performances take place in similarly sized spaces. Although also in-the-round, the 600-seat @sohoplace is far bigger than the Paines Plough’s Roundabout, where the play was originally staged. This means it’s not possible for the performer to greet everyone as they take their seat as was previously the case. But while this plush new theatre is the antithesis of a cramped fringe venue, Donahoe knows how to make it feel intimate. The Stage’s review suggested that Henry does, too.

As the 2023 production of Lemons Lemons Lemons Lemons Lemons at the Harold Pinter Theatre proved, it can be tricky to scale up a fringe show for the West End. Some work can feel overexposed on bigger stages. Every Brilliant Thing doesn’t suffer from that problem.

Like Nassim Soleimanpour’s White Rabbit Red Rabbit, which was staged at @sohoplace last year, it is a formally experimental but, ultimately, accessible play that also offers producers a chance to cast some big names – and charge higher prices. While there are £35 balcony seats available, stalls seats climb up to £95, which I guess is a consequence of the play’s transition into the commercial sector, even if it does seem steep for a solo piece. But the play’s power to knit its audience together remains undimmed, and it’s easy to grasp why this small show has had such a big impact.