What is the author's style in 84, Charing Cross Road by Helene Hanff?

The text unfolds in a series of letters acting as a record of the events occurring in the lives of both Helene and those characters related to Marks & Co. The action unfolds chronologically by individually dated letter rather than by event. For example, when Helene complains of neglect to Frank, it is only in his response to her letter that she discovers Nora has been sick and in need of Frank's attention. The letters also serve somewhat as a twenty-year historical chronicle, from 1949 to 1969. As a result, the reader becomes privy to such information as the impact of rations on postwar London, the re-election of Winston Churchill in 1951, the Brooklyn Dodger's bid for the 1955 World Series, and the 1960 U.S. presidential campaign.