On London North Eastern Railway (LNER) in 2026, seat reservations are strongly recommended but not legally mandatory for every type of ticket. If you purchase an "Advance" ticket, a seat reservation is automatically included and you are required to sit in that specific seat for the journey. For "Anytime" or "Off-Peak" tickets, you can board any train on your route, but you are not guaranteed a seat unless you make a separate, free reservation via the LNER app or website. LNER operates a system called "Seat Sure," which aims to ensure that as many passengers as possible have a dedicated spot. If you board without a reservation, you must look for "unreserved" seating, which is typically found in Coach C in Standard class and Coaches E or M in First Class. During peak commute times or holiday weekends, these unreserved seats fill up within seconds of the train arriving at the platform, leading to many passengers standing for hours. Therefore, while you can technically travel without a reservation, doing so is a significant risk on long-distance routes like London to Edinburgh, where the comfort of a guaranteed seat is well worth the 30 seconds it takes to book one.