The Complete Plain Words is a style guide written by Sir Ernest Gowers and published in 1954. It has never been out of print. It comprises expanded and revised versions of two pamphlets that he wrote at the request of Sir Edward Bridges (then head of the Home Civil Service): Plain Words, published in 1948 as a two-shilling pamphlet aimed at civil servants and An ABC of Plain Words which was published in 1951.
^Gowers, Ernest (1958). The Complete Plain Words (Fifth impression, with amendments ed.). Her Majesty's Stationery Office. pp. iii, 1. "The purpose of this book is to help officials in their use of written English as a tool of their trade."