Update 8 July 2019 on the subsequent merits see  EWHC 1732 (Comm).
In  EWHC 380 (Comm) UCP Plc v Nectrus Limited Cockerill J takes the same conclusion on the new lis alibi pendens rule ex-EU (Articles 33-34) in the Brussels I Recast, which I had suggested in the Handbook (p.182). A court in a Member State seized of an action other than those based on Articles 4, 7, 8 or 9 cannot refuse jurisdiction in favour of a court based ex-EU.
From Herbert Smith’s summary of the case: Nectrus, a Cypriot company, commenced proceedings in the Isle of Man seeking payment of sums withheld by UCP, an Isle of Man company, on the sale of a company, Candor. UCP then commenced proceedings in England claiming that Nectrus was in breach of an Investment Management Agreement (IMA), the loss being the amount by which the sale consideration of Candor had been reduced, hence the amount withheld on its sale.
The IMA contained a non-exclusive jurisdiction agreement in favour of the English courts. UCP disputed the jurisdiction of the Manx court, but in the event the proceedings continued, indicated they would raise the cause of action relied on in the English proceedings by way of equitable set off. Nectrus disputed their right to do so.
Nectrus disputed the jurisdiction of the English court on the basis that the Manx courts were the most appropriate forum to determine the dispute and were first in time.
Other than for the articles listed above, the CJEU’s findings in Owusu continue to apply. That includes English jurisdiction on the basis of non-exclusive choice of court, covered by Article 25 of the Recast Regulation. Justice Cockerill is entirely correct in unhesitatingly (at 39) rejecting forum non conveniens.
(Handbook of) EU private international law, 2nd ed. 2016, Chapter 2, Heading 2.2.4 (International impact of the Brussels I Recast Regulation), Heading 188.8.131.52.2.