Update 7 May 2020 for further specifications followign disagreement between parties, see order made a good week after the first one, in  EWHC 1073 (Comm).
In  EWHC 995 (Comm) Trafigura v Clearlake, Teare J essentially has created a forum necessitatis rule in admiralty, to accomodate the slower availability of the Singapore courts due to Covid19. At 29 ff:
In normal circumstances an Admiralty Court, faced with an application to release a valuable vessel from arrest, would determine whether the security offered was such as to allow the release of the vessel from arrest without delay. In such circumstances there would usually be no need for the court upon which the owner and charterer have conferred jurisdiction to determine disputes between them to find as a fact what security would be judged adequate by the court of the place of arrest to allow the release of the vessel from arrest. For that would in practice be determined by the court of the place of arrest.
But these are not normal circumstances. There is a worldwide Covid 19 pandemic which has disrupted normal life, including the justice system. As a result I was told that the court in Singapore is not able to hear the application to determine the adequacy of the security offered until 18 May 2020. In those circumstances the question arises, or may arise, whether this court should find as a fact whether the security which has been offered to secure the release of the vessel matches that which would be required by the court of the place of arrest or not. That is what this court would have to do, and would have jurisdiction to do, if, unusually, there was no appropriate application before the court of the place of arrest. Those are not the circumstances of this case. There is an appropriate application in Singapore but the result will not be known for almost a month.
At 31 he re-emphasises that comity would ordinarily restrain any jurisdictional temptation. However at 32 he concludes that ‘on the other hand there is a dispute between the owner and charterer. The charterer owes an obligation to the owner to provide security which will secure the release of a valuable vessel from arrest. The owner wishes to enforce that obligation and so to mitigate the losses it is suffering by reason of its inability to trade the vessel. There is therefore a powerful reason for this court, in circumstances where the court of arrest, for understandable reasons, is unable to determine the application for release until 18 May 2020, to exercise the jurisdiction the parties have conferred on it to resolve disputes between owner and charterer.’
Not a jurisdicitional claim out the blue therefore; the choice of court does give England a powerful link to the case.