How has it come to this? That’s what new show Tilting at Windmills finds John Kearns asking, and – after a fashion – it’s what TS Eliot asked in The Waste Land, the modernist poem Kearns deploys here as an unlikely motif. After the breakup of a 12-year relationship with the mother of his son, we find the 39-year-old angrier than usual, and unmoored: flat-hunting pessimistically while living back home with mum and dad, roaming the streets of south London having fled a disappointing walking tour based on Eliot’s verse.

Sound clips of the poem, read by Alec Guinness, punctuate the show. They infuse it (as Van Gogh’s Starry Night did with its predecessor, The Varnishing Days) equally with awe, at life’s ineffable mysteries, and bathos – at the contrast between high literary culture and the humdrum realities of our host’s life. Here he is shopping in Aldi with his mum; there he is naked and not very wet under a dripping shower. A remark about washing machines by a newspaper columnist induces a bout of class anxiety; an awkward teenage meeting is recalled with then-PM Tony Blair, who came to see Kearns’ school play.

Under Jon Brittain’s direction, this all comes at us in Eliot-alike fragments, as Kearns bounces between existential conjecture (an encounter with ventriloquist Nina Conti has him wondering “am I my own puppet?!”) and sadness at the wreckage of his domestic dreams. We’re not let deeply into all that: no oversharer he. But if his real feelings are woven obliquely into this tapestry of a Streatham clown adrift, they remain palpable, not least in the surprising ferocity this usually low-key act brings to his dialogues with dimwit estate agent Connor, say, or with two poetry scholars in a pub over an illicit packet of prawn cocktail crisps.

Maybe its sharp edges, that sense of real hurt beneath the (very funny) gags about Kearns’ limited commercial reach, forestall hilarity. But there’s no resisting the care, the craft and the many beautifully turned phrases of a comic who “feels like he’s being CC’ed into his own life”. At its best, this show about The Waste Land itself aspires to wonderstruck, workaday poetry.