As I predicted, the claim that Cardiff City Football Club intends to bring against Nantes Football Club appears to depend on a chain of causation. Dave Ibbotson is hired by the broker Dave Henderson, the McKays gave the job to the broker, Nantes Football Club appointed the McKays as their sales agent.
There are weak links in this chain. If you approach an Air Charter Broker, you should be able to expect the broker to act in a professional way and only use licenced air carriers. However, if this activity had been going on for a long time, it then becomes more difficult for the McKays to claim that they didn’t know that Henderson was hiring private pilots.
I also think there there is a problem in the link between the McKays and Nantes Football Club. The McKays were hired for the specific task of selling Sala, we don’t know that Nantes Football Club also asked them to provide transportation.