The Bombe Breakthrough is the official guidebook to accompany the Bletchley Park exhibition dedicated to Enigma codebreaking in Hut 11A. The Bombe Breakthrough was based on additional research by Dr David Kenyon, the Bletchley Park historian, and revises and expands on Demystifying the Bombe (2014).
Dermot Turing explains more about the writing of this guide here. You can here Dermot Turing talking about the new exhibition on the Bombe in the video below, or why not visit Bletchley Park and see the new exhibition in Hut 11A for yourself.
The Bombe Breakthrough is available from the Bletchley Park bookstore.