Arthur Sullivan knew better than to mess with a winning formula. ‘Cox and Box, based on J. Maddison Morton’s farce Box and Cox’ reads the title page of his first comic opera, composed to a libretto by F.C. Burnand a good five years before he latched up with W.S. Gilbert. ‘Those boys hit on a brilliant idea,’ Billy Wilder is supposed to have said when he saw the musical that Andrew Lloyd Webber and Don Black had created from his movie Sunset Boulevard. ‘They didn’t change a thing.’ Gilbert’s comic beats are sharper and faster; and he’d doubtless have shortened it by about 15 minutes. But Burnand’s words gave the 26-year-old Sullivan the hook he needed, and on a late summer night at Wilton’s Music Hall, Opera della Luna took it from there. The woman directly behind me started laughing in the overture, and didn’t stop for the full hour.

It’s been said before, but Opera della Luna is a little miracle: a shoestring touring company with a near-supernatural ability to get inside the head (and heart) of 19th-century comic opera. In recent years, they’ve given the UK première of a Johann Strauss operetta, a rare modern staging of the Edwardian West End smash The Arcadians, and an Offenbach double bill that was so raucously, scabrously funny that even writing about it has just made me choke on my tea. Whatever: Opera della Luna just gets it. One or two critics are in on the secret and we exchange furtive grins across the foyer. I’ve no idea what the rest of the profession is doing, but the time of year probably has something to do with their absence. Fake outrage about the Last Night of the Proms won’t confect itself, after all.

Cox and Box gets a head start from being at Wilton’s, a venue so soused in rackety Victorian atmosphere that it might as well be sporting mutton-chop sideburns. In Jeff Clarke’s production, we’re right inside the seedy bedsit that Cox (Tim Walton, dapper and droll in his bowler and three-piece orange check) unwittingly shares with Box (a moon-faced Paul Featherstone, fighting a lugubrious rearguard action against an errant wig). One works nights, the other works days; their landlord Bouncer (Carl Sanderson) gets to double his rent as long as they never meet. ‘Hilarity ensues’ is the relevant phrase here, but it doesn’t remotely do justice to the freshness of Sullivan’s score which, as well as a vigorous dig at the absurdities of Franco-Italian grand opera (‘Rataplan, Rataplan!’ bawls Bouncer, for no particular reason), features what must be the tenderest lullaby ever sung to a rasher of bacon.

The two-piece orchestra divvies it all up between piano and harmonium, whose rheumy wheeze and clattering pedals nail the mood even more perfectly than the various pops, crackles and penny-whistle slides with which the players dub in the sound effects. How can something so simple be so charming, and at the same time so irrepressibly funny? The singing, meanwhile, is exactly as good as it needs to be. Sanderson’s socking great baritone made one fear for the structural integrity of Wilton’s remaining plasterwork, and both Walton and Featherstone sing with a clarity and style that’s all of a piece with characters who pirouette on the brink of caricature, but never slip. After the interval, the same team delivered Offenbach’s one-act farce Les Deux Aveugles with a barrage of trombone gags and Oirish accents so utterly daft that you barely noticed how slight it all was — a rudimentary comic premise, and a couple of perky tunes. Offenbach can get away with it, and Opera della Luna is a gleeful accomplice.

At the Proms, a night of British film music looked on paper like another treat. The scores chosen dated from the late 1940s to the early 1960s: a regular compendium of once-fashionable continental influences in British music. Look! There’s Alan Rawsthorne, channelling Hindemith in The Cruel Sea. Watch in horror, as Elisabeth Lutyens hurls angular 12-tone rhetoric at The Skull! And here’s William Alwyn, going full Sibelius in a massive, brooding cortège from Carol Reed’s Odd Man Out.

The BBC Concert Orchestra finally caught fire in the Alwyn, a high point in an evening of very drab playing, despite the best efforts of the Orchestra’s principal conductor Bramwell Tovey. The percussion section wore straw boaters during Malcolm Arnold’s The Belles of St Trinians but their colleagues were straight-faced and the trumpets, in particular, seemed to be having a thoroughly miserable night. Listen to the film soundtracks of that period, and the one constant is their raw vitality — the sheer urgency of the orchestral playing. This was the BBC Concert Orchestra’s first appearance with Tovey since before the last lockdown, and they sounded like they just wanted to clock off and get back to their sourdough starter.