Grierson coined the term documentary, though he is not the first to use the term. As early as 1902 and 1903 the term documentary was being used. French actualities or newsreels were called "documentary views" or les vues documentaires. In his review of Moana, the film by Robert Flaherty, Grierson said it had a documentary value.

Grierson was very much influenced by political scientist and journalist Walter Lippman. Lippman argued that the system of democracy that emerged after the first world war, that is, parliamentary democracy, representative democracy, democracy in all areas of life—trade unions and the like—did not work well, in part, because democracy had become a very specialized area of activity for a very few people, the ones who got a mandate to represent the masses of people. And the masses for the most part were disinterested or not interested enough and certainly not informed of what was going on in the world. Lippman was rather pessimistic and did not see what could change this situation. His main concern was the lack of information.

At this time cinema was outside the main channels of communication. Newsreels may have presented the events of the day but offered no interpretive analysis. So the cinema at this time was for the most part a purely an entertainment medium.

Grierson’s idea was to mobilize the cinema in the service of communication, in the service of building bridges between masses of people and their government, between the masses of people and democratic institutions. This idea arose in Great Britain and spread to the United States. By the time Grierson left America and returned to Britain, he was full of ideas on how this might be done. And it wasn’t totally theoretical. He had, for example, the model from the Soviet Union. There, the motion picture was being used to advance socialism. Grierson was quite familiar with Soviet films; in fact he prepared the titles for the American version of Battleship Potemkin.

Fortunately, when he returned to Britain he met Sir Stephen Tallents, the director of the Empire Marketing Board, a sort of propaganda and public relations center. It was set up to popularize the notion that Great Britain or the United Kingdom depended very much for its existence on the importation of foodstuffs from all over the world, but mostly from British Empire countries. So this fact of the need to import foodstuffs was the main interest of the Empire Marketing Board. Its goal was to sponsor imports from the Empire and get almost everything which was needed from the Empire.

But to get these products and raw materials you had to know about preservation of foodstuffs, communication with the different centers of production, changes in transport conditions, and so on. So Grierson proposed that film be used as a medium of information, a medium of enlightenment for the people, explaining to them something they didn’t know or didn’t know enough about. This led to the birth of the sponsored documentary film. Not surprisingly, Grierson’s first film was about herring fishermen in the North Sea. Drifters was shown at the London Film Society on the same bill with Potemkin and it had an enormous impact and impression on the public, critics, and future filmmakers—in part because it put average workers on the screen. Ironically, at about the time Drifters was produced, the Empire Marketing Board sponsored another film, a fiction film about the traditional plum pudding on the Christmas table. The idea was to show the different ingredients coming from different parts of the Empire but in the form of a fiction film of the stories of people bringing in the ingredients. It was directed by a feature film director, Charles Crichton, and cost five times as much as Drifters. But more importantly, it was a flop and never received theatrical distribution. By contrast, British Gaumont, a large company with production centers, theaters and its own distribution, contracted to show Drifters. So it was a great victory for John Grierson. In 1933 the Empire marketing Board was liquidated and the film group went to the General Post Office where conditions were much better. They had a studio where they could do synchronized sound.

Most of Grierson’s disciples were young college students, all more or less left-wingers, not revolutionaries but to the left of center and most likely sympathetic to the Labor Party—the opposition party at that time. In fact, from 1930 to 1945, the Conservative Party was in power in Great Britain. Then the great paradox of history occurred. The victorious Winston Churchill, who had one the war, was beaten in the election and Clement Atlee and the Labor Party won government.

Grierson not only invented the sponsored film, he invented at the same time the non-commercial distribution of films. He was the first who initiated showing films regularly in schools, educational institutions, associations, film societies, etc. Toward the end of the 1930's, people who worked for Grierson began to form their own companies like Strand Films. Grierson formed the Film Centre. During the war these same people created the Crown Film Unit which made films for the Ministry of Propaganda. A final thought about Grierson: he did not like elements of fiction film brought into documentary. One such element was the notion of the hero, the individual person being shown in the documentary. Fortunately, not all of Grierson’s disciples heeded his advice.