The languor of Amy Mason’s debut hour may not be for most people, and perhaps that’s part of the point. Free Mason discusses her discovery, in her late 30s, that she’s gay, while married to a man and raising their two children. After she leaves him, we’re invited into a world of late-age personal enlightenment, featuring a hermetically sealed version of Bristol comprising hippies, women who save hedgehogs as a hobby, and a thriving queer scene.

There’s plenty of compelling raw material in Mason’s biography, but rarely does it feel like she monopolises it for any explicit purpose other than to continue a narrative strand that would be considered overly diffuse were it not for her dolorous tones. Her jokes tend to focus on casual wordplay and observation but rarely do they land with a satisfying thud, existing more as callbacks to previous sections of her show rather than pieces that can stand on their own two feet. Lighting schemes also change seemingly at random, in an apparent gesture towards Mason’s theatre-writing background that adds nothing to the staging or, more importantly, the comedy.

When she does strike (as with some solid material about homosexual sheep or affirming her values in a parenting chat group), her deadpan style is able to flourish and the clear intelligence with which she approaches her material becomes more apparent. But much like the airless basement she’s been performing in, this is an hour that could do with cracking open a window to lose its writerly posturing.

Amy Mason: Free Mason, Pleasance Courtyard, until 26 August, 8pm; main picture: Lucy Ridges.