Another long bike ride today, along the canal and over the top of the Braunston tunnel, also visiting a couple of local villages.
The highlight of the day was "Hacker's Challenge". It gave me an MD5, and I had to find out the coords that digested to that md5. The whole point of an md5 digest is that you can't do that, of course.
So I wrote a program that tried a million combinations of northing and westing, until it found the correct md5. And then I found the cache.