This detailed account of the life and people who worked at Bletchley Park is a compelling read, whether or not you are interested in the hardware and technical explanations, of which there is an abundance, but for the personal accounts from those who were involved.
What comes across in these is the extraordinary loyalty and determination of individuals and teams, in spite of the poor living accommodation, welfare and working conditions afforded them in return for their genius and ingenuity.
However, these people fought with their brains. Driven by a collective resolve, winning was cracking a new cipher, which could save hundreds of lives by unveiling a single sentence.
The late Tommy Flowers' section on his work at the Post Office's Dollis Hill research centre using thermionic valves is a fascinating insight as to how it became possible to process data at speeds in powers of ten over mechanical systems, an overture to today's nano-transistor, gigahertz-clocked multi-core power processors.
Combined with the sheer intellectual capacity of the mathematicians working on the project to provide the basis of the programming, this was the key technology that made breaking deeply encrypted messages possible in useable timescales.
It also raises a poignant thought: the `Colossi' - there were quite few of them - seemed to become like trusted old friends, and their destruction after the end of hostilities was viewed by most working with them as a sad affair. Perhaps with 20-20 vision in hindsight, an over-zealous application of the Official Secrets Act, which held back the UK computer industry for decades?
Of interest to historians and the plain curious, this is a quality collection of information on the essence of what made Bletchley Park...and modern computing.