Description:
------------
This may be intended behaviour however the clocks went back on the 29th of November and all date related functions are returning the times minus 1 hour for the entire day (despite the timezone being UTC)



Test script:
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<?php
	date_default_timezone_set( 'Europe/London' );
	$tTime = strtotime("MIDNIGHT");
	echo("Europe/London - " . time() . " - " . gmdate("d/m/Y H:i:s e", $tTime) . "<br />");
	date_default_timezone_set( 'UTC' );
	$tTime = strtotime("MIDNIGHT");
	echo("UTC - " . time() . " - " . gmdate("d/m/Y H:i:s e", $tTime) . "<br />");
?>

Expected result:
----------------
Europe/London         - 1509356919 - 30/10/2017 00:00:00 UTC
UTC                      - 1509356919 - 30/10/2017 00:00:00 UTC

In Both timezones settings.

Actual result:
--------------
30th November

Europe/London         - 1509356919 - 30/10/2017 00:00:00 UTC
UTC                      - 1509356919 - 30/10/2017 00:00:00 UTC


29th November

Europe/London         - 1509271023 - 28/10/2017 23:00:00 UTC
UTC                       - 1509271023 - 29/10/2017 00:00:00 UTC