Heathrow has ordered airlines to cancel flights because it cannot handle the numbers due to travel, scuppering holiday plans of thousands more passengers.
The majority of cancelled flights were on British Airways services.
A spokesperson for Heathrow said the airport asked airlines to remove 30 flights from the morning peak as it was expecting more passengers than it had capacity to serve.
About 13% more passengers were due to fly this Thursday than a week ago, according to the spokesperson, after a surge in late bookings. He said there were enough staff in all areas across the airport to guarantee smooth journeys for the number of passengers in the morning peak, and the decision was taken to avoid unsafe queues.
“We will work with airlines to get affected passengers rebooked on to other flights outside of the peak so that as many as possible can get away, and we apologise for the impact this has on travel plans,” he added.
“We are working hard to ensure everyone has a smooth journey through Heathrow this summer, and the most important thing is to make sure that all service providers at the airport have enough resources to meet demand.”