This boundary marker is no.2 of four that were set up in 1879 when the separate district and parish of Oxhey was created.
Only three of the four survive today, no.3 is located on Chalk Hill and no.4 is located on Aldenham Road.
You're looking for a magnetic nano cache containing a logbook, please log and replace as found, thanks :-)
what3words: ///basic.rental.shell