The essential difference between the church organ and the cinema organ is that the former is intended for the purpose of accompanying choirs, for which it is necessary to build up huge masses of ponderous tone, and, owing to the large spaces and consequence reverberation, any attempt to play rhythmic music is practically hopeless. The cinema organ is designed for entertaining an audience, and its effects must be essentially pleasing. It is more in the nature of a one-man orchestra than an organ, and, apart from the fact that its sounds are produced by organ pipes and it is played from key boards and pedals, it bears little resemblance to the orthodox organ. The combination of the modern electric action and the acoustics of the cinema enable the most amazing rhythmic results to be obtained. When moving pictures were first introduced in the 1900's, it was realised that movies could not be "run cold", some kind of musical accompaniment was necessary to disguise the fact that speech and other essential sounds were lacking.

So the early pictures were accompanied by some kind of an orchestra, usually a trio, who played any kind of music they happened to have, without any idea of synchronising the musical accompaniment to the scenes in the picture. Many ridiculous combinations of picture and music resulted from this haphazard method; pathetic scenes being frequently accompanied or dance music, and vice versa. An orchestra could not be expected to play for eight or nine hours at a stretch, and while they paused for rest and refreshment, some kind of musical accompaniment still had to continue. The result was the introduction of the relief pianist, who would accompany the second feature or the "shorts," the pictorials, comedies, gazettes, etc. As the relief had no one else to follow, he could improvise to the pictures and frequently produce a far more suitable accompaniment, particularly in the comedy scenes. On the other hand, the thinness of tone of the piano by itself in a large cinema let the whole show down as soon as the orchestra stopped playing.

Although large orchestras were used to accompany films, the advent of the depression led to "rationalisation" of the cinema costs which paved the way for the cinema organ or 'unit orchestra'. These organs were developed to imitate the various sections of the orchestra, to allow a single performer to give essentially an orchestral sound. The console was situated in the orchestra pit vacated by the redundant musicians. Television brought an end to the popularity of the big cinema, and the organs and organists fell victims to cost-cutting by cinema owners. The modern tendency to divide the old cinemas into multiplexes was the final blow for the organs, as they had to be removed to make way for building developments. Today few remain in their original homes, and those that have been rescued are installed in halls and museums and lovingly looked after by their devotees.