A Dinner Engagement / Ruth, Cheltenham Town Hall, Cheltenham

Lennox Berkeley was a pal of John Betjeman. So don't be surprised to find, in his music, lines such as "Twenty-five years ago, in my salad days/ In the summer of my time/ When the lemon and the lime/ And the tangerine/ Hung green/ We would regularly greet/ The select and elite/ In a pink marquee/ With toast and tea."

You could take almost any passage from Berkeley's delicious one-act opera A Dinner Engagement and find a similar effect. This culinary delight was first staged at Aldeburgh in Britten's heyday, June 1954, weeks before the lights went up at Sadler's Wells on Berkeley's grand opera Nelson.

It's the Britten-ish quality of A Dinner Engagement that hits you: a similar vivacity, melodic deftness, theatrical sharpness, orchestral brilliance. Paired with Ruth, his biblical opera, A Dinner Engagement makes a diverting Berkeley double bill, with which Michael Berkeley concluded the Cheltenham Festival's tribute to his father, one of its former presidents.

This unforgettable evening was abetted by Richard Hickox, with his knack for throwing light on undervalued British scores, and the City of London Sinfonia, which got its teeth into A Dinner Engagement with a will, bringing out Berkeley's instrumentation with chamber-music clarity.

Berkeley's fecundity of ideas is astonishing: for a quarter of an hour he upstages Albert Herring with glorious pifflings for bassoon and clarinet (and flute in Ruth), plus wonderfully apt, clever string writing. This classy class-comedy centres on a recherché trio down on their luck, who end up entertaining a visiting nabob in their kitchen. The music's a hoot, and with a cracking cast - Roderick Williams, Anne Collins, Robin Leggate and Jean Rigby as the impossible Mrs Kneebone - it's a palpable hit. If it droops at all, it's where Berkeley slows the pace. At full pelt, he's terrific.

Doubts surface in Ruth, a kind of proto-parable that has glorious moments but the odd longueur. The story, in Eric Crozier's marginally plodding libretto, feels just a bit too pi. Berkeley's inspiration seems not so much Les Six as Frank Martin, whose gloomy chromatics can be heard winding their way through decoration and effective ostinati alike.

It features a super aria for Ruth's quasi-sister (the splendidly punchy Claire Rutter) and fine music for Yvonne Kenny's Naomi. The highlights include Pamela Helen Stephen's touching, restrained Ruth and the astonishingly mellifluous part for Boaz, originally sung by Peter Pears and winningly sung here by Mark Tucker.

'A Dinner Engagement' and 'Ruth' will be semi-staged at the Linbury Theatre, Royal Opera House, London WC1 (020-7304 4000) on 28 Sep