Having been unsuccessful with further Googling of the problem I tried manually creating a /usr/local/etc/my.cnf.d
and now the mysql_install_db
command seems to have worked okay. I'm not sure if this is the appropriate solution or if my.cnf.d
not existing is indicative of a deeper problem with the install but, as things seem to be working, I'll mark as resolved.
[Update] As I was a little unsure in my answer whether this was the 'correct' solution I just wanted to confirm that, after a month, everything is still working fine.