BEGIN:VCALENDAR
VERSION:2.0
PRODID:icalendar-ruby
CALSCALE:GREGORIAN
METHOD:PUBLISH
BEGIN:VTIMEZONE
TZID:Europe/London
BEGIN:DAYLIGHT
DTSTART:20250330T020000
TZOFFSETFROM:+0000
TZOFFSETTO:+0100
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=3
TZNAME:BST
END:DAYLIGHT
BEGIN:STANDARD
DTSTART:20251026T010000
TZOFFSETFROM:+0100
TZOFFSETTO:+0000
RRULE:FREQ=YEARLY;BYDAY=-1SU;BYMONTH=10
TZNAME:GMT
END:STANDARD
END:VTIMEZONE
BEGIN:VEVENT
DTSTAMP:20260601T174611Z
UID:castle-x-isa-great-hall-bop-26-sep-2025
DTSTART;TZID=Europe/London:20250926T200000
DTEND;TZID=Europe/London:20250927T183600
LOCATION:Castle Great Hall\, Durham
SUMMARY:[Castle x ISA] Great Hall Bop (26 Sep 2025)
END:VEVENT
END:VCALENDAR