Shared Google Calendar suddenly missing from iPhone

Overnight I noticed that a shared Google calendar that I could normally view on the iPhone Calendar app had suddenly disappeared. This was after months of it working perfectly normally. I double checked all my settings (which turned out to be fine), before heading to Google to try and find a solution.

To cut a long story short, the solution was posted on the Apple discussions site here:

Try to sign-in to your Google account at: https://www.google.com/calendar/iphoneselect and check all shared calendars [you'd] like to see on your iPhone, then tap Save button.

It was as simple as that. After re-ticking the shared calendars on the link above, they immediately started to show up again on my iPhone. I hope that by re-posting this solution here will help others in a similar situation.