Does anyone else get a sense of glee when they're #debugging and realise they've misssed something obvious?

Installing #munin on a new server, wondering why it is not generating graphs.

Hmmm, everything is working fine if I call munin-cron directly, graphs are generated, and the cron entry is there in /etc/cron.d, so what's going on? Why is it not getting run from cron?

$ sudo service cron restart
Unit cron.service could not be found.
$ 

Huh? What is up with systemd? Why can't it find cron? Oh, hang on a second...

$ apt search cron | grep -i installed
$ 

D'oh!