LONDON – British Airways on Thursday won a High Court injunction blocking a threatened 12-day strike by cabin crews that could have grounded about 1 million travelers at the height of the Christmas season.

The decision ended a roller-coaster four days of disputes and negotiations over the planned work stoppage, which threatened to undercut further the already beleaguered airline at one of the busiest travel times of the year.

The strike was called by angry unions in response to British Airways’ cost-cutting decision to reduce cabin crew staffing on most flights. Despite protracted eleventh-hour discussions, Unite, the transport workers union, persisted in calling the strike from Dec. 22 to Jan. 2.

Justice Laura Cox agreed with the airline that the strike ballot was invalid because many votes were cast by members who had left the airline.

Union leaders threatened another strike vote.