The United States and Canada have been having a chance to hear one of the world's most unusual ensembles. Headed by its founder, Jean-Claude Casadesus, L'Orchestre de Lille is a group whose mandate is travel. It is a young orchestra and is one of the few groups today that can proudly claim to have the primary attention of its music director for the bulk of its season.
Mr. Casadesus comes from a musically illustrious family. His uncle was the first director of the famous Fontainebleau music school, founded by the late Nadia Boulanger. His cousin was the renowned pianist Robert Casadesus. His grandfather Henri was a composer, a collector of early instruments, and a viola d'amore soloist when such an instrument was barely known (the earlier years of the 20th century). The Casadesus collection of early instruments has its own exhibition room in Symphony Hall in Boston.
Jean-Claude began his musical career as a percussionist, playing in anything from variety shows (to make money) to Pierre Boulez's Domaine Musicale (to make a name for himself). But, as the conductor related to me in typically (and charmingly) French English this past September, ''When I was 30, I reconsidered the possibility to realize my young boy dream ... to be a conductor. I started to conduct with Pierre Dervaux and Pierre Boulez. I started, in a theater, to conduct operettas, which is a good way to learn (the craft).''
Dervaux then asked him to become his assistant conductor for the Orchestre du Pays de la Loire, then brand new. There, Casadesus got the practical training in ensemble building that enabled him in 1976 to establish his own orchestra in the Nord/Pas-de-Calais region of France. It still goes by its original name.
Casadesus is fully aware how fortunate (and unusual) his position is - being at the head of a musical institution he put together from scratch. ''We are now 100 musicians, middle age of 30 years, 35 women. We play over 100 concerts a year in our region. We have been in Italy, Japan, Hong Kong, Bulgaria, Yugoslavia, and this year, Canada and the United States.
''When we started, there were not a lot of people in our concerts. Sometimes there were more people on stage than in the concert hall. Now we have 5,000 subscribers in Lille (alone), which is a city of 165,000 inhabitants. We have visited about 90 (towns and) cities in our region. We are certainly the most mobile orchestra in France.''
The Orchestre de Lille is unique in that it is truly a regional orchestra. Its home hall may be in Lille, but it spends a good deal of time on the road playing in factories, gymnasiums, churches - anywhere large enough to accommodate the group and a goodly audience.
It must have seemed an improbable idea at first. Could a region that has been badly hurt by France's economic turmoil really care about, and support, a young symphonic ensemble?
Casadesus explains why he thinks it has worked, but he begins with a little philosophy. ''For an artist, you have some questions to answer: What is the necessity of an artist in our society, especially in a society which has been so hurt.
''I think that music, which is an international language, done with sensitivity, soul, and heart ... music can help to nourish and help people bear their bad situations, to be patient, to help to choose new situations. We have discovered that (the people of the region) have a very great need of culture, music, theater, dance companies. My orchestra is absolutely necessary now for that region, for that people.
''They are absolutely with us there.... If one day we had financial difficulties, I am sure I could put 50,000 people into the streets to help us.''
The orchestra is receiving increasing recognition as one of the finest ensembles in France. The vitality and care with which the players work together is amply evident on a recording of Berlioz's ''Symphonie Fantastique'' made for the Harmonia Mundi/France label.
It does not hurt that Casadesus devotes the bulk of his time to the orchestra rather than building career glamour. For him, communicating something meaningful is more rewarding than standing on yet another prestigious podium for a guest stint. He has been tempted at least three times to accept offers to head important French opera companies, but he remains always in Lille.
The Orchestre de Lille finishes up its US-Canadian tour this weekend with concerts at Baltimore's Meyerhoff Hall tonight, Carnegie Hall Friday, C.W. Post College on Long Island Saturday, and at the Kennedy Center Sunday.