Wattmore is a nutcase who sees Satan in the eyes of Cub Scouts. Bolla is a nervy and intense ex-convict. Griffin is resourceful, proactive and loyal but none too bright. The Night Heron, by Jez Butterworth (writer of the recent West End smash Jerusalem), is a character-driven play, powered by the friction that occurs when personalities clash in a confined space. Accordingly, Rabid Monkey Productions concentrate hardest on producing convincing characterisation.

As Wattmore — once a Cambridge University gardener, now something of a pariah — Rob Hoare Nairne is stoop-shouldered: a tall, rangy man too used to making himself appear smaller and less threatening. At once hostile and mournful, he avoids nearly all eye contact — except when gripped by religious fervour.

As Bolla, or Fiona — the new lodger in Wattmore and Griffin’s shack on the marsh, who seems at first to be the answer to their prayers — Kathryn Lewin is in constant nervous motion, pawing at her tracksuit bottoms or flicking her nails against one another. Near the end of the production she takes this to a distracting extreme, contorting both her arms around and about, but for the most part hers is a subtle, focused performance.

As Griffin — who is constantly putting himself at risk to bail Wattmore out of trouble, not that it earns him much gratitude — Jacob Lloyd (pictured with Kathryn Lewin) is saddled with the lion’s share of Butterworth’s trademark quickfire dialogue, and handles it with apparent ease, rattling off lines at speed without ever tripping or becoming difficult to understand.

There’s just one disadvantage to this performance-focused approach to the play, which is that the big picture — the pacing, the arc of the plot — is neglected. The production putters along like a little two-stroke engine, moving at a decent enough pace to maintain our interest but never slowing down or speeding up, even for the climax, which sails by almost unmarked.