In his bomber jacket, librarian spectacles, crew cut and awkward grin, Paul Heaton could hardly look less like a pop star. Yet see past this unpromising exterior and it is difficult to dispute the fact he has been one of British pop's most routinely underrated figures of the last three decades.
Heaton recently returned with What Have We Become, a collaboration with Jacqui Abbott, his former co-vocalist in the Beautiful South. The album went top three in its week of release – behind only Coldplay and Michael Jackson, as he reminds us tonight with relish – and confirms that the spiky yet honey-voiced Abbott has always been his most effective musical foil.
If Heaton were a dramatist, he would surely be Mike Leigh. The songs from all stages of his lengthy career boast observational acumen, dry wit and a big heart. New track Costa del Sombre is a sensitively empathic portrait of a middle-aged woman on a package trip throwing herself into a Shirley Valentine-type holiday romance with dancefloor "steps she had been saving up since 1972".
Co-fronting their six-piece band, Abbott is vivacious and full-voiced on DIY, a sardonic country-tinged diatribe written from the perspective of a wife traded in for a younger model. When they plunge into the pop alchemy of the Beautiful South's back catalogue, as with the gorgeously melodic Rotterdam, you recall exactly why their 90s greatest hits collection went platinum five times over.
A 23-song set has virtually no filler, and they close with a sweetly harmonious revisit of the Housemartins' 1986 a cappella No 1, Caravan of Love. Paul Heaton would doubtless be horrified to be categorised as a national treasure. Sadly for him, he has no real say in the matter.
• On 29 May. Box office: 0114 2212828. Venue: the Leadmill, Sheffield.