Feed from iCal is 1 hour behind or ahead on iOS - Things to Check
On iMac
In Preferences please check that your "Date & Time" settings are as below:
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Also make sure that your Timezone is set correctly
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On iOS (iPhone / iPad)
To save battery life, a number of iPhone/iPad users turn off "Setting Time Zone", however this is needed to automatically update to Daylight Saving.
To address this:
If you go to Settings -> Privacy -> Location Services -> System Services > Setting Time Zone - this should be turned ON - see below
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IMPORTANT: Having made these changes remove the feed from your calendar and then re-add it.
Hopefully this will resolve the problem for you but if not please do get in touch.
In Preferences please check that your "Date & Time" settings are as below:

Also make sure that your Timezone is set correctly

On iOS (iPhone / iPad)
To save battery life, a number of iPhone/iPad users turn off "Setting Time Zone", however this is needed to automatically update to Daylight Saving.
To address this:
If you go to Settings -> Privacy -> Location Services -> System Services > Setting Time Zone - this should be turned ON - see below

IMPORTANT: Having made these changes remove the feed from your calendar and then re-add it.
Hopefully this will resolve the problem for you but if not please do get in touch.
Updated on: 10/11/2022
Thank you!