These days, shows about care homes, dementia and end of life are very common, but when Iain Heggie’s splendidly named Wiping My Mother’s Arse premiered in 2001, it was ahead of the curve. It is set in an overstretched nursing home where Andrene (Anne Kidd) has developed a close relationship with her care worker, Larry (Johnny McKnight), little realising he previously spent five years living with her son, Derek (David Rankine). Cue the comedy of confusion and subterfuge.

The play’s fault line runs through questions of care, compassion and money. The emotionally detached Derek has been happy to farm out the care of his mother while he lives at the other end of the country. He shows less interest in her welfare than he does in her bank account.

Any compassion comes from Larry, who has the measure of Andrene’s short-term memory lapses, as well as the sense to recognise her moments of lucidity. Derek’s new love interest, Kath (Lisa Livingstone), also unaware of his history with Larry, is torn between empathy and acquisitiveness: if she sticks with Derek she could be in for a tidy inheritance.

If this were a play to wear its politics on its sleeve, it would be about the monetisation of care. Even the unworldly Larry makes constant reference to money, either playing teasing games with Andrene – who has lost all sense of the price of things – or, more riskily, flushing out his ex-partner by making suspicious bank withdrawals. Andrene can only complain about her lot in a place where everything is about efficiency and routine, and nothing about family and home.

These ideas are there, but it is not that kind of a play. Updated by Heggie to the era of podcasts, vapes and voice messages, it falls awkwardly between farce and drama. Sam Hardie’s spirited production is frequently funny, whether it is the running bad-taste amputee gag or Andrene’s “catastrophe bag” malapropisms. But it also has more sobering concerns about abusive relationships, homophobia and alienation that are at odds with the playwright’s lighter tone. It is a play of some charm that never quite lives up to the subversive promise of its title.

• At Pitlochry Festival theatre until 5 September