By the time this post propagates the problem might likely be solved, but it’s worth a mention for poor plebs like me who spent their whole morning trying to find out what’s going on.
iCal on Apple Mac can’t delete calendar entries from connected Google Calendars.

From a user’s point of view, the problem is simple: some users tried to sync iCloud and it wiped out all their Google Calendar entries.
So Google took the strange step (in my opinion) of disallowing the delete command from all iCal users.

In my office this technical glitch surfaced last Sunday and so far the gremlins have not been caught.
It’s only the delete command that doesn’t work for us though; creating and editing events still seem to work as expected.
So what happens? The annoyance manifests itself when trying to delete an entry.

The circular update icon starts up next to relevant calendar, which is nice.
But then the dreaded triangle appears with a message that gives a bit of disinformation as to what’s actually wrong:
“The server responded with an error: the calendar https://www.google.com/calendar/dav/randomstring@group.calendar.google.com/user/ was not found on the server. Make sure the URL is correct“
Via my browser, I quickly logged into Google Calendar, where I was happy to find that my calendar is in fact on the server. The clue that something else was amiss.
After deleting and reconnecting the iCal Google Calendar accounts on 2 other office computers with no difference, I finally googled “iCal Google Calendar doesn’t update” and stumbled upon Google’s “Known Issues” page, which shed light on the problem.
So now we just have to wait for the fix. Hope it doesn’t take too long, Google.
Very interesting tip mate. Do you know who the rugby world champions are by the way?