A two stage multi with a short walk between the listed coordinates and the final.
I love this little double anachronism in the heart of our village. From the listed coordinates you should be able to see an information device that we no longer use. Interestingly, their name lives on in our vocubulary in general, and in geocaching vernacular in particular. The device refers to three locations, and one of these has also been consigned to history, wiped off the map by an act of parliament more than 40 years ago.
Let ABCD be the digits at the listed coordinates. Read left to right, top to bottom. Ignore the letters that are present, they are not relevent to calculating GZ.
The cache is located at:
S 34º 49.(C - D)(B/2)(D - 2A) E 138º 53.(B/C)(D/A)(D + 1) Checksum of minute decimals is 16.
I hope you enjoy your visit to Gumeracha.