There is something unusual about the gathering in the foyer of the Barbican’s subterranean cinema one cold Tuesday evening in early March. It is the buoyant mood. We are all so obviously happy to be here – remarkably so, considering that we are about to sit through Mariah Carey’s ill-starred big-screen debut, Glitter. If you haven’t seen it, and chances are that you haven’t, the film is a truly wretched vehicle for the unaccountably popular singer, a kind of dumbed-down A Star Is Born transposed to the New York music scene of the 1980s.

We take our seats, and the atmosphere of bonhomie continues. As she urges me to try a cake that an audience member has baked just for tonight, Nicko Vaughan, one of the event’s hosts, explains: “Yes, there’s a camaraderie here. It’s really the Blitz spirit, I suppose, people pulling together cheerfully in the face of shared suffering.”