I’ll preface this by confirming that I have solved 10A though not 10B. But if Harry lets this through I would like to share a little rabbit hole the 10.1 Case File led me down. The file suggested that I conduct a ‘say what you see’ Google search, and I saw a Ford key with the letters HA inscribed, so a quick Google led to some links comparing different Ford keys; in particular the HA key was apparently a ‘40-bit’ key!
Of course this is a competition ahout classical cryptography so I should have stopped there, but I couldn’t help investigating modern 40-bit encryption since after googling the title ‘The best-laid plans’ I came across the following quote paraphrased from Robert Burns’s most famous poem: ‘The best laid plans of mice and men often go awry’, the namesake of the famous American novella. This quote is almost exactly 40 bits (39 bits)! I just wanted to share this little red herring I came across for anyone who might have also been misled by it; the correct interpretation of the hint is not so convoluted. Good luck to anyone still trying!
Love it! Half the fun is to be found in the hunt. Hope you get something from 10B too! Happy Christmas, Harry