The Coptic British Orthodox Church does use an adaptation of the Greek St. James (which differs from Syriac St. James), but it should be noted that the theory of its use early on in Britain is nothing more than speculation on their part. There is no evidence nor early tradition for the use of St. James in Britain or the West early on. Rather, the tradition refers to three other liturgical streams: that of St. Mark through Alexandria into Milan, that of St. Peter into Carthage and Rome, and that of St. John from Ephesus into Gaul, Britain and Spain.
The B.O.C. St. James is interesting as it is the Greek St. James (again, different than the Syriac St. James) but with Coptic hours of prayer, vestments, and calendar, but with feasts of Western saints added along with some Western hymns.
The St. James is also blessed for use by ROCOR parishes. There is also another translation of the St. James done at New Skete monastery (OCA).
It is a long liturgy, and communion is given after the canons for this liturgy - the Body is received in the hands, which are made into a throne.