Estoppel – Convention. The claimant company's administrators issued proceedings against the defendant arising out of its failure to pay US$65m under a foreign exchange transaction, which had mistakenly been paid to the claimant's parent company. The defendant relied on defences including estoppel and waiver, discharge and satisfaction. The Commercial Court, in dismissing the claim, held that the parties had been acting on the understanding that the transaction had been closed. Accordingly, the defendant had established estoppel by convention, but other legal doctrines, including estoppel by representation, acquiescence and silence, might well be equally applicable. However, the discharge and satisfaction defences had not been made out.