London is exactly 1 hour behind Paris year-round. When it's 3:00 PM in Paris, it's 2:00 PM in London. Both cities observe daylight saving time on the same schedule.
London uses Greenwich Mean Time (GMT) in winter and British Summer Time (BST) in summer, while Paris uses Central European Time (CET) in winter and Central European Summer Time (CEST) in summer. The 1-hour difference remains constant.
Any business hours work well! With only a 1-hour difference, 9:00 AM - 5:00 PM London corresponds to 10:00 AM - 6:00 PM Paris. Full business day overlap.
London and Paris are connected by the Eurostar train (2h15m), making same-day business trips common. The time difference is minimal enough to coordinate seamlessly.