Following Alex’s answer I was able to resolve this issue; seems this to be an issue non specific to the packages being installed but of the permissions of homebrew
folders.
sudo chown -R `whoami`:admin /usr/local/bin
For some packages, you may also need to do this to /usr/local/share
or /usr/local/opt
:
sudo chown -R `whoami`:admin /usr/local/share
sudo chown -R `whoami`:admin /usr/local/opt