Secret wartime projects in code-breaking, radar and ballistics produced a wealth of ideas and technologies that kick-started the development of digital computers. Alan Turing took an early lead on the theory side, along with fellow mathematicians on both sides of the Atlantic. This is the story of the people and projects that flourished in the post-war period. By 1955 the computers produced by companies such as Ferranti, English Electric, Elliott Brothers and the British Tabulating Machine Co. had begun to appear in the market-place. The Information Age was dawning. Before the market passed to the Americans, for a brief period Alan Turing and his contemporaries held centre stage. Their influence is still discernible deep down within today's hardware and software.