Another Biggles an Swallows And Amazons reader here!
Books that began to really make an impression on me were Aldous Huxley's Brave New World, George Orwell's 1984 and, for social commentary, The Road To Wigan Pier. However, the book that really imprinted my 'world view' was Robert Tressall's The Ragged Trousered Philanthropists, with its incisive explanation of the workings of capitalism.
Later, I also took in Herman Hesse, Satre and even some Nietzsche. The latter leading me into an interest in philosophy.
steve