In Quota Quickies: The Birth Of The British 'B' Film, Steve Chibnall discusses the films released in the aftermath of the 1927 Cinematograph Films Act. The Act required UK cinemas to screen a quota of British films, to avoid Hollywood productions dominating the market. The result, however, was an influx of low-budget and low-quality films that have been been maligned by critics ever since.
Chibnall re-evaluates the extant films of the period, including a case-study of the early films directed by Michael Powell. He also provides statistical analysis, albeit from a data set that's limited to cinemas in Leicester.