A summer of travel chaos could be ahead for thousands of holidaymakers after British Airways failed in a High Court bid to block pilots strikes which may coincide with a series of other walk-outs involving airport workers.

BA had attempted to block industrial action over a pay dispute after the British Airline Pilots’ Association (Balpa) announced its members backed the move by more than nine to one, on a turnout of 90%.

BA claims the strikes are designed to cause “the maximum in disruption” and could cost the airline up to £40 million a day.

On Tuesday, BA applied for an interim injunction to prevent strike action by pilots based at Heathrow and Gatwick, arguing that Balpa’s ballots did not comply with trade union law.

Following a hearing in London, Mrs Justice Elisabeth Laing dismissed BA’s application for a temporary injunction, ruling that Balpa was “more likely than not” to establish at a full trial that its strike ballots were properly issued.

It comes after union Unite said Heathrow Airport could be “shut down” this summer as 4,000 workers including security guards, engineers and drivers prepare to strike on July 26 and 27, and August 5, 6, 23 and 24.

  • ITV News Correspondent Juliett Bremner on what we know about when the strikes could happen

Unite said the action follows the rejection of an 18-month pay offer amounting to £3.75 extra a day for the lowest paid.

The union claimed there is growing frustration over pay disparities between workers doing the same job, as well as the "massive" pay package earned by Heathrow chief executive John Holland-Kaye, whose basic remuneration rose from £2.1 million in 2017 to £4.2 million last year.

Unite predicted the walkout "could potentially shut down the airport".

In the British Airways case, a High Court judge gave permission for an appeal against her ruling, which could be heard by the Court of Appeal as early as this Friday or at the start of the following week.

BA applied for an interim injunction to prevent strike action by pilots based at Heathrow and Gatwick Credit: Steve Parsons/PA

Balpa agreed to give an undertaking to the court that they would not issue a notice of industrial action pending the outcome of any appeal.

In a statement after the ruling, a BA spokesman said: “We are very disappointed with today’s decision. We will continue to pursue every avenue to protect the holidays of thousands of our customers this summer."

In a statement, Balpa general secretary Brian Strutton said: “While we’re pleased with the judge’s decision, we’re frustrated that time has been wasted.

“BA could have spent this time coming back to the negotiating table instead of trying – and failing – to tie us up in legal knots.

“This delay will now continue with BA seeking to appeal against the High Court’s decision."

He added: "The company itself has admitted that even one day of strike action would cost more than what our pilots are asking for, so the ball really is in their court here, to look after their pilots and ensure the hardworking public get to continue their holidays as planned."

BA’s barrister John Cavanagh QC earlier told the court that Balpa had not provided a list of the categories of employees who had been balloted, and did not indicate when the strike action would take place. He said it was “likely to commence on or about August 7”.

Mr Cavanagh said: “There can be no doubt that the timing of the action is deliberate and designed to cause the maximum in financial loss and disruption for BA, and the maximum in disruption and hardship for BA’s passengers (and those they are going to visit), plus business partners and other employees.

“The action is due to commence in peak holiday period, in the middle of school summer holidays, and at the busiest time of BA’s year.”

He said there was “no doubt that if the industrial action takes place there will be very grave disruption indeed”.

Mr Cavanagh added: “It is impossible accurately to assess BA’s financial loss if the industrial action were to go ahead, save that it will be very substantial indeed, running to £30-40 million per day.”

Balpa’s barrister Simon Cheetham QC argued that trade unions have “a degree of discretion as to how it categorises workers”, and that Balpa “was only required to set out general job categories”.

He said the level of detail BA argued Balpa was required to provide amounted to “a disproportionate interference with the right to strike”.

Mr Cheetham added that Balpa had not yet decided when strike action would take place, and that the union “wishes to have the power to call industrial action at any time during the period between August 7 and January 21 (2020), the maximum period during which the ballot is valid”.