PHP date/time conversion example

datetime.php

<?php

foreach (range(1, 12) as $m) {
    $elStart = new \DateTimeImmutable("2019-{$m}-10 23:50:00", new \DateTimeZone('Europe/London'));
    $elEnd = $elStart->add(new \DateInterval('PT5H'));
    $utcStart = $elStart->setTimezone(new \DateTimeZone('UTC'));
    $utcEnd = $elEnd->setTimezone(new \DateTimeZone('UTC'));
    printf("E/L: %s / %s,  UTC: %s / %s\n",
        $elStart->format(DATE_RFC822),
        $elEnd->format(DATE_RFC822),
        $utcStart->format(DATE_RFC822),
        $utcEnd->format(DATE_RFC822)
    );
}

/*
 *
 
 Outputs

 E/L: Thu, 10 Jan 19 23:50:00 +0000 / Fri, 11 Jan 19 04:50:00 +0000,  UTC: Thu, 10 Jan 19 23:50:00 +0000 / Fri, 11 Jan 19 04:50:00 +0000
 E/L: Sun, 10 Feb 19 23:50:00 +0000 / Mon, 11 Feb 19 04:50:00 +0000,  UTC: Sun, 10 Feb 19 23:50:00 +0000 / Mon, 11 Feb 19 04:50:00 +0000
 E/L: Sun, 10 Mar 19 23:50:00 +0000 / Mon, 11 Mar 19 04:50:00 +0000,  UTC: Sun, 10 Mar 19 23:50:00 +0000 / Mon, 11 Mar 19 04:50:00 +0000
 E/L: Wed, 10 Apr 19 23:50:00 +0100 / Thu, 11 Apr 19 04:50:00 +0100,  UTC: Wed, 10 Apr 19 22:50:00 +0000 / Thu, 11 Apr 19 03:50:00 +0000
 E/L: Fri, 10 May 19 23:50:00 +0100 / Sat, 11 May 19 04:50:00 +0100,  UTC: Fri, 10 May 19 22:50:00 +0000 / Sat, 11 May 19 03:50:00 +0000
 E/L: Mon, 10 Jun 19 23:50:00 +0100 / Tue, 11 Jun 19 04:50:00 +0100,  UTC: Mon, 10 Jun 19 22:50:00 +0000 / Tue, 11 Jun 19 03:50:00 +0000
 E/L: Wed, 10 Jul 19 23:50:00 +0100 / Thu, 11 Jul 19 04:50:00 +0100,  UTC: Wed, 10 Jul 19 22:50:00 +0000 / Thu, 11 Jul 19 03:50:00 +0000
 E/L: Sat, 10 Aug 19 23:50:00 +0100 / Sun, 11 Aug 19 04:50:00 +0100,  UTC: Sat, 10 Aug 19 22:50:00 +0000 / Sun, 11 Aug 19 03:50:00 +0000
 E/L: Tue, 10 Sep 19 23:50:00 +0100 / Wed, 11 Sep 19 04:50:00 +0100,  UTC: Tue, 10 Sep 19 22:50:00 +0000 / Wed, 11 Sep 19 03:50:00 +0000
 E/L: Thu, 10 Oct 19 23:50:00 +0100 / Fri, 11 Oct 19 04:50:00 +0100,  UTC: Thu, 10 Oct 19 22:50:00 +0000 / Fri, 11 Oct 19 03:50:00 +0000
 E/L: Sun, 10 Nov 19 23:50:00 +0000 / Mon, 11 Nov 19 04:50:00 +0000,  UTC: Sun, 10 Nov 19 23:50:00 +0000 / Mon, 11 Nov 19 04:50:00 +0000
 E/L: Tue, 10 Dec 19 23:50:00 +0000 / Wed, 11 Dec 19 04:50:00 +0000,  UTC: Tue, 10 Dec 19 23:50:00 +0000 / Wed, 11 Dec 19 04:50:00 +0000

 *
 */