Colombo is 5 hours 30 minutes ahead of London during GMT, and 4 hours 30 minutes ahead during BST. Colombo uses Sri Lanka Standard Time (SLST, UTC+5:30) while London uses GMT/BST. When it's 12:00 PM in Colombo, it's 6:30 AM (GMT) or 7:30 AM (BST) in London.
Sri Lanka does not observe daylight saving time while the UK does, so the difference varies between 4.5-5.5 hours throughout the year.
Best calling time: 2:30 PM - 10:30 PM Colombo time. This corresponds to 9:00 AM - 5:00 PM in London, covering UK business hours.
London and Colombo share historical ties from the British colonial period. Sri Lanka has a significant diaspora in the UK, and direct flights connect both cities in approximately 10.5 hours.