Why is Google Calendar reminding me it's "Easter Sunday" on 19 Jan 2016?
I appear to have at least discovered where this reminder has originated from: in the Google app (formerly "Google Now"), under "Reminders", there is a "Past" reminder for "Easter Sunday (Apr 05 2015)".


Past reminder

However, there is no "Upcoming" (current) reminder listed here for "Easter Sunday" - so nothing should be appearing in the calendar. The two (recurring) Google Keep reminders (mentioned above) are the only two reminders listed under "Upcoming". So, it's still a mystery why this "Easter Sunday" reminder appears to have suddenly recurred after an unusual time period.

Partial solution:

Tapping this "Past" entry simply gives the option to delete it. Which I have, and now it's gone from the Google Calendar! It's just a puzzle as to why (and how) it happened?