‘If contracting parties agree to give a particular court exclusive jurisdiction to rule on claims between those parties and a claim falling within the scope of the agreement is made in proceedings in a forum other than that which the parties have agreed, the English court will ordinarily exercise its discretion whether by granting a stay of proceedings in England or by restraining the prosecution of proceedings in the non-contractual forum abroad or by such other procedural order as is appropriate in the circumstances to secure compliance with a contractual bargain unless the party suing in the non-contractual forum, the burden being on him, can show strong reasons for suing in that forum. I use the word ‘ordinarily’ to recognise that where an exercise for discretion is called for there can be no absolute or inflexible rule governing that exercise.’