Many thanks to Andrew Savage and Nick Payne for flagging  EWHC 1968 (Comm) Bestolov v Povarenkin a little while ago, and for sending me copy of the judgment at the time. Apologies for late reporting: frustratingly even at gavclaw we cannot always devote the amount of time to the blog we would wish. Dr Maganaris in the meantime also has summary here.
As readers no doubt are aware, the Brussels I Recast Regulation (Article 62) does not define ‘domicile’: it defers to national private international law on the issue. The Civil Jurisdiction and Judgments Order 2001 establishes that a person is domiciled in England for the purpose of the Brussels Regulation (recast) if: the person is “resident” in England; and (cumulatively) the person has a “substantial connection” to England. Bryan DJ takes us through the relevant (and often colourful) precedent and notes, importantly, at 28 that the consequence of the English rules is that the same person can be resident in two different jurisdictions at the same time. At 44, he summarises with a list of criteria, and decides on the facts of the case that Mr Povarenkin is indeed domiciled in England (the substantial connection test having been more easy to determine than that of residence).
Subsequently the High Court reviews at length whether there was a valid choice of court agreement under Article 25 of the Regulation – which at this jurisdictional stage of the proceedings Bryan DJ decides there was not (choice of law for the relevant contracts being English law, was justifiably not considered definitive in this respect), at least not clearly. Obiter, the judge reviews forum non conveniens, at lenght in fact (and in a very clear way with a keen eye on relevant precedent as well as court practice in England) however he holds both before and after the obiter that evidently given Owusu, forum non conveniens has no calling.
A well written judgment, the approach of which on domicile evidently goes beyond having relevance merely for the English courts: for under the Regulation, courts in other Member States, too, may have to consider whether parties are domiciled in an EU Member State other than their own including, for the time being, the United Kingdom.
(Handbook of) EU private international law, 2nd ed. 2016, Chapter 2, Heading 2.2.3, Heading 188.8.131.52.