The idea of anyone laughing at Ciro Pandice, Fernando Carpineti or any other member of the 20-strong Experimentum Mundi orchestra is in itself laughable. Any one of the men on stage could lift a quartet of music critics with one hand while continuing to play with the other and hurl them from press seats to foyer. Never before have musicians had such brawny arms, stubby fingers and tough skins. Never before has a composer chosen to form an orchestra made up entirely of craftsmen (and some of their wives), who ply their skills on stage, and in doing so make music.
Opera is, of course, the plural of opus, Latin for work. In Battistelli's unparalleled opera, performers work. Literally. On stage, and throughout the performance, Pandice lays bricks. He lays nine courses before the final note. Carpineti shapes stones. Elsewhere on the stage, Edouardo Borgiani, a blacksmith, batters away at his forge, Giuseppe D'Anella and Oberdan Carpineti grind knives, Sergio Leandri cobbles shoes, the Sannibale brothers - Alfredo and Fabio - build barrels, and Luigi Battistelli makes pasta.
In this opera, to work is to play; to play music based on the insistent rhythm of the sounds of traditional craftsmen at work. The remarkable thing is that it works so powerfully and so convincingly. Experimentum Mundi is, without doubt, high calibre music. It is also a celebration of the accidental music produced by men working with skills that are fast disappearing.
"I wanted to capture these sounds," says Battistelli, "and orchestrate them into something special. In some ways Experimentum Mundi is a memory of small-town sounds I have stored away since childhood. In others, it is purely a musical performance."
It is also memorable theatre. Watching Battistelli's performers make music as they make useful, even edible, things is a captivating experience. There is so much to watch; yet close your eyes and the rhythms of the sounds they make drive along as headily as Wagner in full flight or as gently as The Magic Flute, although Battistelli is more school of Stockhausen than Mozart or Wagner.
How did Experimentum Mundi come about? "Giorgio came to make tape recordings of us at work in Albano," says Sergio Leandri. "At first we thought he was mad. But because we all know Giorgio - he was brought up here with us and some of us went to the local primary school with him - we just accepted that this was the sort of thing he did."
"When we first played Experimentum Mundi together," says Guido Salustri, fellow cobbler, "we recognised it straightaway as music."
"Not that avant-garde music or opera are my kind of thing," says Fernando Carpineti, sharpening his chisel. "I prefer reggae."
As the performers settle down to rehearsals in Carpineti's farmhouse here in the sweet-smelling vineyards on the slopes of Albano, Battistelli tells his version of the story of Experimentum Mundi.
"I was born here in Albano; I've known these people all my life and the sounds they made as they worked stayed with me all the way through my time at the Academy of Music in Rome. It took two years to write the piece. That was when I was 28 and 29. The first performance was in 1981. We continue to perform it when asked."
What happens when the craftsmen hang up their hammers and chisels? "Well, we are already into the second generation," says Battistelli. "You see Oberdan [the knifegrinder] over there? He's 24, the youngest of the team and, to date, has only played twice; so, perhaps, we will go on into the next century with these age-old sounds."
Props for the Almeida rehearsals - sand, stones, brick, cement - arrive on the back of a mud-splattered Toyota Hilux station wagon lurching across the evening fields. Food - vast quantities, all of it fresh and home-made - is prepared in the kitchen above the performers' heads by mothers in striking floral frocks and gum-chewing daughters in miniskirts, fishnets, stacked-heels and shades.
The men drink strong, home-made amber wine interspersed with long draughts of mineral water, guzzled straight from the end of a hosepipe - the hills of Albano are alive with the sound of gurgling mineral water, and of swifts mewing, children shouting, dogs barking, goats belching, Alfas rasping, tractors chugging... and a prima donna budgie that whistles and trills mellifluously throughout the evening.
The scene is one a Covent Garden set-designer could only dream of and it does seem a shame that it cannot be brought shoe, chisel and barrel to the Almeida. When the performers are dressed (dirty blue, grey or brown overalls), Battistelli opens the pages of his inscrutable score, raises his tapering hands and Experimentum Mundi saws into cacophonous life, building slowly and insistently into an unbreachable wall of rhythmic sound as the rehearsal gets into full swing.
The mothers cooking are forced to shout at one another above the noise of forging and hammering rising up to the kitchen, while the daughters shriek into the mouthpieces of their mobile phones (no self-respecting Roman teenager is without one). Dogs and cats scrap in the yard.
"Piano, piano," Battistelli calls, not at the cooks, pets, budgie and women, but at the cobbler duo. A little less coopering here, a little more blacksmithing there, a touch more pasta-making and knife-sharpening. The knife grinders, pedalling their machines, lean down as if choreographed to turn a page of Battistelli's enigmatic score.
Ian McDiarmid, the Scottish actor and Almeida director, reads the freshly translated English libretto that ducks and weaves through the pulsating percussion ("It hardly matters what I say in the rehearsal; no one here speaks English and the volume is too great anyway - on stage I'll be wired up to a microphone").
When the sound abates and Battistelli is satisfied that the barrels made, shoes repaired and roads laid have produced good music, trestle tables appear, groaning in an instant under Beano-sized dishes of pasta, risotto, grilled meats, tomatoes, bread, tiramisu, cheeses, fruits and salads. Strong fingers hold cigarettes and glasses of wine, jokes are told and dogs crunch fleshy bones under the table. Above this evening chorus, the Battistelli-beating budgie trills avian arias into the black, bat-filled sky. The satisfied conductor, sitting in the middle of this rural bacchanalia, is very much at home.
'Experimentum Mundi, Almeida Theatre, London, N1 (0171-359 4404) 6,7 Jul