Ultimately Lumley was successful in securing damages from this fact scenario. It was not an appeal. How did Lumley win?

LUMLEY V GYE (1853) 118 ER 749 (QB)

An opera singer named Johanna Wagner agreed to sing for one season with the plaintiff's company, Her Majesty's Theatre. Ms Wagner broke that promise after being offered a higher fee to sing with the defendant's company, the Royal Italian Opera. The plaintiff suffered a financial loss as a result of losing Ms Wagner's services. He sued the defendant for inducing breach of contract.

The plaintiff was able to satisfy most of the requirements of that tort: (i) the defendant knew of Ms Wagner's contract with the plaintiff, (ii) the defendant persuaded and caused Ms Wagner to break her contract with the plaintiff, and (iii) the plaintiff suffered a loss as a result of the defendant's intervention. The court nevertheless rejected the claim on the ground that the defendant had acted in good faith. He honestly believed that Ms Wagner had not been paid by the plaintiff and that she therefore was entitled to terminate her contract to sing at Her Majesty's Theatre. The defendant therefore did not have (iv) the intention to cause a breach of contract