Tommy Flowers (https://en.wikipedia.org/wiki/Tommy_Flowers) knew a thing or two about valves (and how reliable they were if not switched off!). We have him (amongst many others) to thank for the success of Bletchley Park.
Old thread now - but I just got this book and it's made my day! I'm of that vintage where my first coding was on a friends Nascom I (not mentioned in the book) but I really cut my teeth on the school's commodore Pet!
I remember looking at adverts for the SCMP and the MK14 with envy tho!
As someone who started coding just before the zx80 arrived I fully appreciate the difference he made! I was reading ETI (if you don’t know what the stands for you are too young :) that had adverts for the MK14 which was the predecessor to the zx series ) when it all kicked off and I was in awe! A true innovator.