As the ROCOR hieromonk referred to (inaccurately) in a number of posts above, please let me make a few corrections of fact:
1. While part of our family originated in Cornwall, and I have lived in Cornwall (and Devon), I wasn't born in Cornwall, so that's as good as that gets.
2. Archbishop Hilarion has never to my knowledge authorised the Liturgy of Saint John (the Divine) aka Stowe for use in his diocese.
3. We did a rescension in English, of the Stowe Missal Liturgy with the object of seeing if it could be made usable for 21st century people. It is NOT a purists version - but a close adaption. Due to the absence of rubricisation, we "adapted back" a few of the Sarum rubrics which possibly originated from Stowe or its contemporary British cousins.
Someone asked when the Stowe Liturgy was superceded by the Roman liturgy. It wasn't. The Liturgy of Saint John the Divine was suppressed by the schismatic Norman bishops in 1171. One assumes that there wouldn't be much point in suppressing something that was no longer in use, so it seems reasonable to assume that in some last corner of Celtic Britain, it was in use up until 1170-71ish. It was superceded by Sarum which owed its existence to various stages of development from the SJD Liturgy the beginnings of which are evident in the Stowe book) via much Continental Gallican and Roman borrowing.
I would advise against anyone taking the maelruin version and its attendant suppositions too seriously. I have severe problems with his translation in places (and no, I haven't the faintest intention of entering a debate on that subject). Suffice to say the following:
We need to remember that Stowe is merely a representative book from the many local variations on what may be termed the "British Isles Liturgy". The Church in the British Isles seems to have collectively referred to its Liturgy as the Liturgy of Saint John - meaning Saint John the Divine. They maintained that their earliest liturgical material came from Ephesus at the time that Saint John was living there. Whether that is true or not, is of no consequence - it's as good as the attributions of other Orthodox liturgies. I think that translating the Latin and choosing artificially Byzantine-compatible phrases only distorts the feel of the Liturgy - away from the Celtic feel. Having said which, our own rescension certainly uses English which is un-Celtic in feel.
The Stowe book itself is a book with a long - three hundred year history of use and alteration. It is a Irish version of the Saint john Liturgy, and it certainlyevidences having resided in several different places. It was added to, overwritten and generally has an interesting tale of the development of the Liturgy to tell for the paleographer, since many of the overwritten texts are discernible using modern technology (sometimes just the Mark 1 eyeball).
It is also worth remembering that when Saint John Chrysostom wrote that the Church in the British Isles albeit differing in some administrative details etc., was still wholly Orthodox - thiswas the Liturgy that was being used in Britain. So by extension it might be said to have his imprimatur ... sort of ...