If Francois Truffaut was its passionate voice, Alain Resnais its fastidious diplomat and Jean-Luc Godard its (gifted) nutty professor, Bertrand Tavernier is the raging motor mouth of French cinema. No French politician - or, indeed, international politician - who is an enemy of cinema is safe from his torrential rebukes; no critic incapable of sharing his generous embrace of both old and new waves can duck his exasperated scorn.
Exceptional among French cineastes, he is an eloquent defender of English cinema of the past ("Pink String and Sealing Wax. A masterpiece! Went the Day Well - an English village squire collaborates with the Nazi invader. Superb! The Fallen Idol. Wonderful!").
And, for seven years, as a member of three French pressure groups, he has been the Asterix clobbering Jack Valenti, chairman of the ruthlessly colonising Motion Picture Association of America. Since Tavernier also has something of the bulk of an Obelix this can be no mean pummelling.
A motor mouth is often nothing more than vanity on speed; the information trite, the emotional content thin. None of this is true of Tavernier. In 21 films, covering a great range of subjects, including family relations (Sunday in the Country), jazz ('Round Midnight) and a Simenon drama (The Watch- maker of St Paul), his emotional involvement is powerful.
But it is when the subject also ignites his sense of social injustice that you get both barrels of his indignation - as in his new film, Ca Commence Aujourd'hui (It All Starts Today).
When directors make films with a political spin-off their public campaigning often turns out to be rooted more in film promotion than any lasting commitment to the issue. But with Tavernier the creative process of making a film seems to engender an ever deeper involvement with the reality his fiction is drawing on. It was true of The Undeclared War (the plight of veterans of the Algerian war) and it is true of his latest film.
This deals with the issue of the lack of effective support for teachers and schools. Philippe Torreton plays a head teacher in a school in northern France who becomes hopelessly engulfed in the personal problems of pupils and parents; he is frustrated by parsimonious funding, enraged by bureaucratic shiftiness.
This is a Blackboard Jungle for the end of the century. The twist is that the students are not thuggish teenagers but infants, the eldest aged four. Tavernier takes one of the miracles of the French education system, the ecole maternelle, and demonstrates that "If you only concentrate on the blackboard and ignore the environment," paradise becomes hell. The environment here is an area where unemployment is three times the national average. The script was co-written by Tavernier's son-in-law, Dominique Sampiero, a teacher.
"The ecole maternelle," Tavernier says, "is of crucial importance because it represents The Birth of a Nation" - (Film reference is a standard element in French eloquence). "It is a demonstration of equal opportunity at its earliest point." But it was a horror story told to Tavernier by his son-in-law that convinced the director he had to make this film. One of the young mothers, whose heating and light had been cut off during the winter months, killed herself and her children.
Tavernier kneads his fists agitatedly, as if the tragedy were his. "This was something that hurt me as a man, as a father. Something which made me ashamed of my country. I did not know it was possible in France to cut off someone's heating and lighting in winter. But I learned that the EDF (the French national electricity company) has a trick of cutting it off in autumn and not putting it back until spring so they can say: `But we didn't cut if off in winter!' "
Since the film was finished last year, Tavernier and his team have taken part in more than 200 public discussions on the problem. Now, he says, a law is under discussion to prevent this abuse. "But you don't make such a film out of wanting to deliver a message," he insists. "You make it out of compassion for the characters, out of respect for the teachers whose teaching work is crushed by social problems. You make it out of love and out of anger, not to be preachy."
He launches into a story of how he made a short documentary about a wretched modern housing project in the suburbs of Paris - with the EDF again having an unlovely involvement. He managed to get prime minister Lionel Jospin to see the film - he then wrote a letter to the chairman of EDF who sent a cheque for nine million French francs to help the project.
"Isn't it a pathetic illusion of film-makers," I ask, "that their work can really achieve any permanent change?" He has a good answer: "Would the absence of film change more?"
"But surely," I say, "the EDF chairman was playing the routine con of getting the heat off one problem while doing nothing for about 500 others?"
"I know, I know the limits," Tavernier says, his voice positively tragic. "But a film can throw light on a problem and, in France, with our chains of art cinemas, we can have discussions after the screenings across the whole country and in that way turn it into an event."
Tavernier is uneasy about a development that stems from this. "I am a film-maker, not a politician," he complains. "As film-makers we should not be doing this job. We are not paid to do it, we are not elected to do it. In the past artists became angry about certain issues. But this is different, people are beginning to count on us to do this job."
About the other political battle - to save European cinema from the Americans - Tavernier tells of a projected international business agreement which had outraged filmmakers worldwide. "French filmmakers discovered," he said, "that international experts - experts built the Titanic! - answerable to no one, elected by no one, had drafted a law, the Multinational Investment Agreement.
"One feature of this trade agreement was that if, for example, the French gave aid to an African film director, Steven Spielberg could say: `You gave money to a Malian director, so you have to give me money too.'
"That is the best way of cutting off financial aid to film-makers. French politicians knew nothing about this. We actually had to give a copy of the text to the minister. We had enormous support from the Canadians, the Australians, the New Zealanders."
And the English? This provokes a cyclonic outburst. "Tony Blair," he says, "was a total ally of the Americans. He should have a visiting card saying: `I would give away all the films that have made the glory of England for any American film.' In his attitude he is the valet of the Americans. He could take lessons from Churchill!"
The law was shelved. "So you were victorious?" I ask. "I would just say they are trying less to destroy us because of the more redoubtable problem the film industry has with the Internet. They thought that perhaps it is better to leave some liberties to European film-makers."
When you are with a well-rounded personality performing with enormous energy it is only later you wonder: what makes him the way he is? What makes him so driven?
The answer comes accidentally when I ask him about his father, indirectly the subject of his These Foolish Things (with Dirk Bogarde playing the dying father). I am curious about a man who had been a poet, and who had courageously edited a literary magazine during the German occupation. What happens in later life, I wonder, to people who for one brief period live a life of intense significance and then settle into routine living?
"He was the most educated, most literate man I have ever known," Tavernier said. "But the problem with my father was that he was a superb storyteller who put most of his talent into his life. He was president of Pen Club [the international writers' association], of course, in the Sixties and Seventies, and fought for Cuban and South African writers. But his real pleasure was to go out to dinner and tell wonderfully funny stories."
Then he makes the confession, unselfconsciously: "All my life," he says (he is now 57) "has been a reaction against this. I work furiously. I do a lot of things. I believe less in the things that you talk about than the things that you do. I believe in action."