This year, as you can hardly fail to have noticed, has been officially designated the Centenary of the Cinema, which makes it a good time to reflect, not only on the triumphs of the medium, but also on its dear departed - those hundreds upon hundreds of films, particularly from the silent era, which have failed to survive.

With the coming of sound, silent films were assumed to be of no further interest, or commercial use (the same was the case with black-and-white television after the advent of colour), so they were often recycled for the chemicals in the filmstock, or simply destroyed. It was not until the 1930s that the first archives were set up, by collectors like the 21-year-old Henri Langlois, and even this did not ensure preservation because of the fragility of nitrate film. The archive collections, predictably underfunded, continue to decay.

This is a serious matter for students of film, because it means that our assessment and undersanding of film history must be even more tentative than otherwise. We tend to assume that the best has survived; but whose “best”? Judgments vary with time. Remember, Jean Renoir’s La R gle du jeu (1939), which now figures on most lists of the world’s greatest films, was considered a flop on its first release; and historians estimate that as much as 60 per cent, or more, of French cinema production from the 1930s is, in the archivist’s phrase, “not available for study”, that is, lost.

However, the archives serve an essential purpose for students, who can view the film (for a price, after taking their turn on the waiting list). They also supply the needs of cinema clubs and venues like the National Film Theatre, the Museum of the Moving Image, the Cinemath que and so on. Whoever doubts the importance of such places to film culture has only to consider the role played by the Paris Cinemath que in the training of the film-makers of the French New Wave. Eccentric and chaotic though the place was under Langlois’ guidance in the 1950s and 1960s, it offered a huge programme of films from all times and places to anyone who chose to walk in for the price of a packet of cigarettes.

Nowadays, we have television. But television - despite Channel Four and BBC2 - doesn’t like subtitled films, and has increasingly to worry about the size of its audience; and, at the same time, there has been a steadily expanding cinema audience since the mid-1980s, which shows by its presence in the cinema that it realises that seeing a film on the small screen is not the same as seeing it on a big one, especially in the case of black-and-white or silent films. This is why it is important to keep on reviving old films, allowing them to be seen in proper conditions by new generations of filmgoers.

That there is an audience for these films, in an overall British cinema audience that has doubled in the past decade, is shown by the number of theatrical re-releases in the past few years. French cinema features strongly: we have had new prints of Jean Renoir’s Une partie de campagne, Le Crime de Monsieur Lange and Boudu sauve des eaux, Jean-Pierre Melville’s Le Samourai, Louis Malle’s Ascenseur pour l’echafaud, Jean-Luc Godard’s Alphaville, and more. The audience is usually happy to accept this, without bothering too much to wonder why these films should have been chosen for re-release at this time, or how they emerged from wherever they had been hiding onto the screen at the local independent cinema.

The answers have to do with the least exciting topic in film and media studies, which is distribution, a matter not only of getting the film from the producer to the exhibitor, but also, in the case of old films, locating prints, clearing rights and advertising the work to its potential audience. All this sounds pretty routine, until you think that the rights to some masterpiece of world cinema (even if a print of it still exists), may be in the hands of an eccentric millionaire who has no wish to sell them and can’t even be bothered to answer the distributor’s letters; or else held by someone who sticks doggedly to a vastly inflated idea of what they are worth.

In either case, the masterpiece remains unseen. Heather Stewart, head of distribution at the British Film Institute, was amused by the results of a survey in the January issue of Sight and Sound, inviting comment on the “BBC 100” - the Corporation’s choice of films to mark the Centenary. A few of the respondents expressed surprise that some film or other had been admitted, as though the BBC were free to choose and show its ideal selection of works from the past hundred years. In reality, as BBC2 film programmer Steve Jenkins rather coyly remarks, “the fact that the BBC does not have access to every film ever made means that we can only feign a degree of subjectivity.”

Just so. The BBC can’t show films to which Channel Four holds the rights. For Heather Stewart, at the BFI, picking films for theatrical re-release is anything but “an idealist choice”, but first and foremost a matter of taking advantage of opportunities to acquire rights as they come up. The secret, however, may be to make it seem otherwise: a television company which has the rights to a particular film will find ingenious ways of scheduling it in the context of seasons (film noir, animal movies, two-headed directors . . .), to make it look as though the movie has been especially chosen to fit that slot. This is quite different from the work of the archives or the NFT programme planners. The archive has a brief to preserve as much as possible of the British film heritage, so it is concerned mainly with acquiring prints. This puts it at the mercy of donors, but not rights-holders, since its films can only be shown to researchers or in certain “designated venues”, like the NFT.

BFI Distribution, on the other hand, is in the business of giving wide screenings to newly released and re-released films, and it has to consider its costs. Even if a rights holder is sensible and prepared to sell the UK distribution rights for a reasonable sum (usually for five, but sometimes for seven or ten years), the distributor has to recover this from the audience, taking between 25 and 50 per cent of the money that goes through the box offices of the rather small number of repertory cinemas still left in this country.

Before that, there will be investment in striking a new print, which can easily cost Pounds 3,000. The film will have to be publicised, in listings magazines which may charge Pounds 700 for a quarter-page ad. A poster must be designed and printed, at a cost of Pounds 2,500 for a poster in full-colour - which is why the BFI sticks to monochrome - and there will be flyers to print and distribute. Finally, there will have to be press shows, for magazine reviewers, followed in the week of release by a show for reviewers in the daily and weekly newspapers, in preview theatres which cost Pounds 120 an hour.

“It’s very much a hit-and-miss thing,” says Andi Engel of Artifical Eye, one of the most admired among the few remaining British independent distributors. “We had lovely successes with (Marcel Carne’s) Les Enfants du paradis and (Jean Vigo’s) L’Atalante, but the Renoir - Boudu sauve des eaux - didn’t work at all; and to release an old film is not that much cheaper than to release a new, smaller film.” The essential nowadays is to combine theatrical release with release on video, and the independents now all have their own video labels: Connoisseur (BFI), Artificial Eye, Electric Pictures. The relationship is symbiotic: according to Engel, without the publicity generated by a theatrical release, the video won’t sell, while “the video gives a chance to recover some of the costs if we don’t succeed in the cinema”. The exception is American films, where it is almost impossible to acquire video rights, so Engel is planning theatrical release only for a group of American classics that he has just acquired (including North by Northwest and Touch of Evil).

BFI Distribution is unlike other distributors, being publicly funded, and it will not compete with Artificial Eye or Electric for rights. “We’re not in a position to be doing the really big revivals and we’re supposed to applaud the other distributors for reviving films, not to be bidding against them,” Stewart says. On the other hand, she prides herself in being “canny” about identifying works whose moment has come again, but which no one else is after. An example is Georges Franju’s Les Yeux sans visage, which BFI will re-release this month: “not Les Enfants du paradis, but a very strong art-house classic.” Later this year, she is going to release four films by Ritwik Ghatak - described by fellow Bengali Satyajit Ray as “one of the few truly original talents in the cinema that this country has produced”. She is a good deal less certain about the box office success of this “unknown, art-house, utterly fantastic Bengali film-maker”, hardly seen internationally outside film festivals. Because there are no English subtitled prints of his work in the West, the dialogue has had to be transcribed and translated for the re-release, and the costs have been “phenomenal, really unbelievable”.

They would still seem trivial to the major Hollywood film distributors, who can spend Pounds 1,000,000 on publicising a film in the UK (the alleged figure for the release a few years ago of Total Recall). The independents represent a tiny fraction of the total cinema market (around one per cent) - yet, for anyone who cares about cinema, they perform an absolutely vital service, in recovering and re-releasing renowned classics (Les Enfants du paradis) for generations that have not seen them, or less known cult films (Les Yeux sans visage), or the work of foreign directors who are entirely new to audiences here (Ritwik Ghatak).

It is not only a question of giving us the chance to see these films in the cinema, but also the fact that theatrical re-distribution, unlike NFT seasons or television screenings, attracts critical reassessment. The film that is reshown in such circumstances has an authentically public airing, allowing the works of Carne, Franju, Renoir and Vigo to live again. After all, you would hardly bother to describe a television broadcast of one of these directors’ films as “a revival”, would you?