All Eurostar tickets include a specific reserved seat, and initially you'll be allocated seats. When you buy tickets at www.eurostar.com, you can change your allocated seats by clicking Change seats after payment and selecting specific seats from a numbered seating plan.

Yes, you are officially required to sit in your allocated seat on the Eurostar. This is particularly important on the high-speed London-to-Paris or London-to-Amsterdam routes, as the train is often fully booked and staff use the seating chart for manifest and security purposes. In 2026, Eurostar's policy is that passengers in Eurostar Plus and Eurostar Premier can change their seats for free via the "Manage My Booking" tool before they pass through the ticket gates. However, once on board, you cannot simply move to an empty seat in a higher class or even within your own coach without permission, as that seat may be reserved for someone boarding at a later stop (like Lille or Brussels). If you find your assigned seat is broken or there is a specific comfort issue, you should speak to the Train Manager before moving. Failing to sit in your assigned seat can lead to confusion during ticket checks and may prevent staff from delivering pre-ordered meals to the correct passenger in premium cabins.