Can anyone recommend a more technical book on the design and operation of the Colossus? I've found Colossus, a collections of essays edited by B. Jack Copeland, but not much else, at least on Amazon. (Also interested in anything on Zuse's computers, as I've mostly studied the Atanasoff-Berry Computer and Eniac).
the bletchley park trust sells (used to?) pamphlets in the gift shop that they call "reports" which have been written by some of the rebuild team and other associates.
I think the national library (whatever it is called) has the actual operation manual available.
But this should be what you're looking for?
https://publish.fid-media.de/entities/book/f1548ef2-2420-4c9...
How about this one, although it covers the context of the times…. https://www.amazon.ca/Colossus-Bletchley-Parks-Greatest-Secr...