Security guards at London's Heathrow Airport, Europe's busiest, will escalate their strike action over pay into the busy summer months, the U.K.'s largest trade union said Wednesday.
The Unite union said more than 2,000 of its members will walk out for 31 days from June 24 through to Aug. 27, a move that could wreak havoc for the millions of people going through Heathrow during the summer travel season.
