I would think it all depends how the contract was written. I have read here in the past that Luton had the option to cancel the contract in I think 2015. When this was threatened Abertis said they would demand £300m in compensation.
So does the contract allow Abertis to sell their concession seeing that they did not buy it but gained it when they took over TBI? If it does is it written into the lease that the new operator has to be approved by the owners of the airport first? What if the new operator does not want to expand the airport could the council block it by invoking the 2015 rule? I think lawyers will be carefully reading the small print in this one.