“when the defendant has submitted to the jurisdiction of the foreign court, then he cannot be heard to say that the court has no jurisdiction to decide the issues raised by the proceedings in which the submission was made. The remaining question is what the scope of those issues was…..it is easy to see why different and unrelated claims should not be taken to be within the scope of the submission. But equally, in my judgment, it is impossible to say that claims which are directly concerned with the same subject matter should not…..[That] approach holds good, in my judgment, where the [party] makes a related claim in the sense discussed in the United States authorities and reflected in our own RSC Ord 16 r 8(1)(c): ‘any question or issue relating to or connected with the original subject matter of the action’. Whether a particular claim should be regarded as related in this sense must always be a question of fact and degree.”