“What is it with this new trend of having to shout in order to prove you’re angry?” asked Mrs Chrisparkle slightly tetchily over our interval Pinot Grigio during last Sunday’s performance of Proof. “The young woman in this play shouts in just the same way the young woman in A Taste of Honey did. Makes my head hurt!” “Funny you should say that”, I responded, “as A Taste of Honey was directed by the same person, Polly Findlay”. Her eyes widened as if she had just stumbled over the most fabulous Eureka moment. “Well”, she concluded, “she needs to find another way to help actresses express anger”.

I have to agree. From the opening scene, where Catherine, played by Mariah Gale, is conversing with her father Robert, played by Matthew Marsh, it was instantaneously noticeable how many more decibels were emanating from Miss Gale’s diaphragm than from any of her fellow actors. I immediately got a sense of imbalance, and, although I got used to it after a while (quite a long while) I could never stop thinking that her performance was a bit shouty.

But really, I should start with the play. David Auburn’s Proof won the 2001 Tony Award for Best Play and that year’s Pulitzer Prize for Drama. It’s a tight, compact little play, with some clever twists and nice garden paths to lead you up. It tackles some interesting subjects – the inability to continue working when you’re suffering mental illness, the fine line between genius and madness, the inheritability of mental illness, sibling rivalry, and the question of how do you prove that you had a genius idea first or that someone else stole it. Helen Goddard’s set is a feast for the eyes and really accurately suggests a rather decrepit back patio. I also liked how the play manipulates time, with present, past and imaginary all having their place.

But I have two major problems with the play. It’s very slow to start – and, apart from the clever twist in the first scene, the first half hour or so is actually quite boring. There doesn’t seem to be much in the way of dramatic intensity between the characters and simply increasing the shoutiness levels is no replacement. It doesn’t get going until the argument between the two sisters, which reveals much more of their characters’ natures. The character of Hal, played by Jamie Parker (who you can always rely to put on a fine performance), is very thinly drawn and you get precious little understanding of his character or motivations from the text.

My other problem is the ending. The whole basis of the play concerns the authorship of a brilliant piece of mathematical proof, apparently discovered by the ailing Robert during a burst of lucidity whilst suffering from mental illness. But did he really discover it, or was it actually the work of his – maybe – equally brilliant daughter? And how can you prove who came up with the proof? How much more intriguing it would have been if the ending had been enigmatic – suggesting one resolution, whilst giving evidence in the other direction, so that you kept on guessing during the train ride home. But no – Mr Auburn makes it very clear in the final scene exactly who it was that came up with the proof and frankly I was disappointed.

Mariah Gale’s Catherine has a very convincing abrasiveness when dealing with characters or subjects she doesn’t like and her mood swings are very well portrayed, shoutiness aside. However, we both felt much more in tune with Emma Cunniffe’s performance as the bossy sister Claire, determined to get her own way despite a pretext of caring about her sister’s well-being. She gave a great performance of controlled exasperation and bullying. Jamie Parker breathed as much life into the role of Hal as possible and was immensely watchable as usual. Matthew Marsh, who we enjoyed in The Last of the Haussmans, brought depth and understanding to the difficult role of Robert.

Not a bad production by any means, but sadly we both came away from this with feelings of general dissatisfaction.

P.S. Please, Menier, could you put the heating on? That auditorium was freezing! Mrs C kept her Danish High-Tog jacket on throughout the whole show and the man next to her was huddled in overcoat and scarf! When he nodded off we weren’t sure if it was boredom or hypothermia.