Hoar's Lane might be considered a linking byway between two roads, but a glance at the map shows that it is actually part of a continuous trackway that runs from (at least) Preston via Offley Holes and then beyond along Carter's Lane (aka Wibbley Wobbley Lane) past Pirton to Shillington and beyond. The lane is perhaps an ancient cartway dating back to medieval times. It crosses another ancient road from Hitchin to Offley. While parts of the hedgerows of Hoar's Lane are indeed old, there has been some recent replacement and there you can find an unusual hedgerow shrub, the Spindle Tree which has bright pink tricorn seed pods in autumn.
As to the cache, you will be looking for a small pill bottle with a security cap hidden in a big tree. No pen so bring your own. Easily accessible even for children. Just make sure it is well hidden from passing muggles after you have signed the log.
PS. I have no idea why it is called Hoar's Lane.