The Court of Appeal has now confirmed in  EWCA Civ 2011 Vik v Deutsche Bank that permission for service out of jurisdiction is not required for committal proceedings since the (now) Article 24(5) rule applies regardless of domicile of the parties. See my posting on Dar Al Arkan and the one on Dennis .
Gross LJ in Section IV, which in subsidiary fashion discusses the Brussels issue, confirms applicability to non-EU domicileds however without referring to recital 14, which confirms verbatim that indeed non-EU domicile of the defendants is not relevant for the application of Article 24.
(Handbook of) EU Private International Law, 2nd ed. 2016, Chapter 2, Heading 184.108.40.206.