Can a judgment be enforced against a person represented in but not a party to the action?

While leave was not required to enforce the judgment in representative proceedings as against the parties actually before the court, as against a person represented in but not a party to the proceedings, the judgment could be enforced only with the court’s leave. On such an application, the validity or the binding character of the judgment could not be challenged by the person against whom it was sought to be enforced, for he was bound by the estoppel created by the judgment; but he could escape having such a judgment enforced against him if it was fraudulently obtained or otherwise by reason of facts and matters particular to his case, most commonly, that he was not a member of the class represented in the action at the time when the cause of action arose: Commissioner of Sewers v. Gellatly (1876), 3 Ch. D. 610 at 615 and 617.