Can you please try to insert this into the .ics file:
BEGIN:VTIMEZONE
TZID:Europe/London
BEGIN:DAYLIGHT
TZOFFSETFROM:+0000
RRULE:FREQ=YEARLY;BYMONTH=3;BYDAY=-1SU
DTSTART:19810329T010000
TZNAME:GMT+01:00
TZOFFSETTO:+0100
END:DAYLIGHT
BEGIN:STANDARD
TZOFFSETFROM:+0100
RRULE:FREQ=YEARLY;BYMONTH=10;BYDAY=-1SU
DTSTART:19961027T020000
TZNAME:GMT
TZOFFSETTO:+0000
END:STANDARD
END:VTIMEZONE
right after the X-WR-TIMEZONE:Europe/London line, and check if that fixes Outlook.
15MtA5fPyKWn3c7J9NSSisSNZL3Qaz7ayU
