Best overlap: 2:00 PM to 6:00 PM in Colombo is 8:30 AM to 12:30 PM in Manchester.
Shoot for 2:00 PM to 6:00 PM in Colombo; your Manchester colleagues will see that as 8:30 AM to 12:30 PM. A 4-hour overlap gives you a workable daily window; aim for earlier in it to avoid clipping the end of someone's day. Daylight saving complicates things slightly: Manchester observes it, Colombo doesn't, so the difference flexes by an hour part of the year.
London to New York is five hours apart, except for the five weeks a year when it isn't. Exact overlap windows for every US zone, the 2026 DST mismatch dates, and where to put the recurring sync. -