“The decision of the Court of Appeal in Studham v. Stainbridge [1895] 1 Q.B. 870 is authority for looking at the substance rather than the form in deciding what the subject matter of proceedings is, and in our view a further test is to consider what a judgment will be held to have decided for the purpose of a plea of estoppel. Section 53 of the Evidence Act provides that- “Every judgment is conclusive proof, as against parties and privies, of facts directly in issue in the case, actually decided by the Court, and appearing from the judgment itself to be the ground on which it was based.”