Transport troubles have made it hard for people to return to work after the jubilee weekend.
The staffing issues that have plagued the airline over half-term continued to cause EasyJet to cancel more flights on Monday. The airline canceled more than 80 flights on Sunday, causing thousands of passengers to change their plans.
Some customers were stranded abroad at the end of the half-term holiday due to the airline's cancellation of flights.
Workers shortages as international travel rebounded have been blamed by airlines and airports for most of the recent disruptions.
An easyJet spokesman apologized and said the airline was extending its customer service. EasyJet carries almost 300,000 customers on more than 1,700 flights. The challenging operating environment has led to the cancellation of 37 flights today.
Several flights were canceled on Monday. The airport that was most affected by easyJet's cancellation said it was operating normally.
Over the next six weeks, Eurocontrol warns that there could be insufficient capacity to cope in some areas. The period was likely to be very challenging for most airports.
The reopening of Terminal 4 will relieve some of the pressure on check-ins and security for other airlines.
While we are still years away from passenger numbers returning to pre-pandemic levels, reopening Terminal 4 will give airlines at Heathrow extra space across the airport, which will help them manage the impact additional travel documents continue to have on check.
Thousands of passengers for London waited hours until Sunday evening to board trains because of power failures on the line north of Paris.
Many passengers in London were forced to travel on to crowded buses and busy roads because of the tube strike.
The strike was the latest in a series of actions taken by the members of the union. The effects of tube strikes have been lessened by the ability of many people to now work from home, as well as the availability of the new Elizabeth line, which like overground services continued to run as normal.
After the weekend's parties and parades, Paul Glennon, a construction worker in central London, told the PA news agency that it was "back to reality". It was a terrible nightmare.
The construction worker, who was waiting at the Paddington station, said it was chaotic. There were a lot of people in the street. I don't know where to start.
The strike was a show of strength, according to the union. Mick Lynch said: "We will not rest until we have a just settlement to this dispute and we urge the mayor to stand up to the Tories who are cutting funding to TfL rather than trying to pick a fight with tube workers."
Most of the tube stations were kept open in areas outside zone 1 in the city centre. There will be some disruption until about 8am on Tuesday.
Services in Yorkshire were affected by the Arriva drivers strike.