This paper has two related purposes. First, our goal is to explain the results of recent research on twentieth century British (as well as American) English, using equivalent corpora of general written (published) English known as the 'Brown Family' of corpora. Limiting our attention to British corpora, the 'Brown Family' contains three matching corpora of a million words each, the BLOB, LOB and F-LOB corpora, sampled at roughly thirty-year intervals (1931±3¹ years, 1961 and 1991). (A fourth corpus from 1901±3 is under development, and one-third of it will be used in the latter part of this paper.) These enable us to trace the changing history of written (published) British English over a sixty-year period. Through changes in frequency in grammatical categories and constructions across a variety of genres, we observe largely consistent patterns of change which lend themselves to explanations in terms of what may be called general stylistic trends. To these trends we give such names as colloquialization (movement towards spoken norms of usage), densification (movement towards denser or more compact expression of meaning) and democratization (the trend towards avoidance of discrimination or inequality in the linguistic treatment of individuals). Only the first two of these trends will be explored in this paper. In the second part of the paper, we show how general stylistic norms, such as are provided by the 'Brown Family' corpora, can be used as a reference norm against which statistical deviations identify some of the characteristic features of style of an individual author or an individual text. For this we make use of Rayson's Wmatrix software (http://ucrel.lancs.ac.uk/wmatrix/) for comparing (groups of) texts in terms of lexical, grammatical and semantic characteristics. Although the comparison is in some respects lacking in accuracy, it identifies typical style markers of an individual text, ordering them in terms of their differentness from the reference norm. It remains to be seen how far this computational technique can place the elusive notion of authorial style on an objective footing, but results so far are promising.