The idea here is to synchronise your Google calendar(s) with your N9 (and presumably N950 since they both run MeeGo Harmattan), which isn't that hard in itself. What caught me out and had me searching was how to sync all my Google calendars with the phone.
In its most basic form, this system allows you to sync just your main Google calendar with a mobile device.
On your phone, go into "Accounts" and start setting up a new CalDAV account:
https://www.google.com/calendar/dav/Tap on the "Sign in" button and you will be presented with a page allowing you to set up the scheduling (just like with any synchronised account) and showing you the calendar that's going to be synced and added to your phone's calendar:
Point your browser (mobile or desktop, it doesn't matter) at this URL: