If your flight is cancelled at London Heathrow (LHR) in 2026, you are protected under UK Passenger Rights (UK261). The airline is legally obligated to offer you a choice between a full refund or being re-routed to your final destination on the next available flight (even if it's with a rival airline, provided they can get you there significantly sooner). While you wait, the airline must provide a "duty of care," which includes vouchers for food and drink, two phone calls or emails, and overnight hotel accommodation (including transport) if the new flight is the next day. If the cancellation was within the airline's control (e.g., technical fault or crew shortage) and you were given less than 14 days' notice, you may also be entitled to monetary compensation ranging from £220 to £520 ($280–$660) depending on the flight distance. However, "extraordinary circumstances" like extreme weather or air traffic control strikes exempt the airline from the cash payout, though the "duty of care" remains mandatory regardless of the cause.