According to the Oxford Guide to the Book of Common Prayer: “Resolution VIII of the 1867 Lambeth Conference made provision for this, provided that any change or addition was consistent with the spirit and principles of the Book of Common Prayer.” This presumably refers to the 1662 edition, although I would greatly like to know what the opinion of that conference was on the Scottish Episcopalians and the Protestant Episcopal Church. A discussion we could have would be to enumerate BCP editions as canonical or not, using this resolution as a basis. But I propose that since in many cases, there were changes, but the editions in question are widely accepted by traditional Anglicans, for example, the 1928 American Book and the 1962 Canadian Book, perhaps we should instead enumerate two lists, a “Yellow List” of problematic service books which have been in some cases retrofitted to be consistent with the spirit and principles of the Book of Common Prayer, and a “Red List” of books which are not canonical, in that they are fundamentally incompatible with the Book of Common Prayer. For the Yellow List, I can think of a few examples, chiefly the 1979 American book, which while hugely problematic, includes rubrics which allow for the restoration of a modicum of sanity, something accomplished by the Anglican Service Book of 1994 (which can be downloaded entirely on Google Books from a university library; if you lack this access, the most important parts can be found here http://justus.anglican.org/resources/bcp/Anglican_Service_Book/index.html I am also leaning towards classifying the ponderous two volume 1984 Welsh BCP under this category, but the work is so massive I need more time for the task. On the Red List, I would put all non-traditional services from the C of E Common Worship, and its predecessor the Alternative Service Book, and the Canadian Alternative Service Book likewise, and I would also include all subsequent emendations of the Episcopalian liturgy in the US, and all recent liturgical texts of the Scottish Episcopal Church and the Province of Ireland, for example, the dreadful 1994 BCP. I think the prayer book of the CSI also belongs on at least the “yellow list” and quite possibly the “red list”, because it was the first major liturgy heavily influenced by the modernist liberal faction of the Liturgical Movement (which should not be confused with earlier so-called liberals as Rev. Percy Dearmer, who were not modernist in any sense), and introduced celebration versus populum, the bane of contemporary liturgy in the Western church (before that time, there were only a handful of churches in the world, mostly in Rome, where architectural constraints forced the altar to be placed in such a manner, mainly for the benefit of pilgrims, as these altars following the ancient custom, implemented in the Roman church in the second or third century, that all altars contain the relics or be atop the relics of martyrs (later expanded to saints in general), in memory of the evil persecutions of Christians that became so severe after the death of Marcus Aurellius; these churches in Rome feature a dip in front of the altar called a “confessio” enabling pilgrims to get as close as possible to the various beloved martyrs entombed underneath these altars, a bit less practical than the Eastern practice of putting only small relics in the altars and setting out the remains in general of the glorified saints where they could be venerated in reliquaries present in the nave, or in Coptic churches, in shrines). Also the CSI to its discredit if memory serves allows some congregations to practice adult Baptism and take a Baptist Zwinglian or Memorialist interpretation (not due to the Baptists IIRC but rather the missionary churches of the Stone-Campbell Movement, also known as the Disciples of Christ). And I think we can agree the New Zealand BCP also belongs on at least the yellow list, if not the red list. I have not read either the Australian prayer book or the book used in the diocese of Sydney; if anyone knows where those might be obtained, I would be very interested. In like manner, I know of where a great many liturgical texts are to be found, for example, most Anglican service books are here: http://justus.anglican.org/resources/bcp/england.htm The CSI liturgy is in part here: http://www.csimichigan.org/Liturgy.htm ~ By the way, I would urge members caution with regards to older prayerbooks, or prayer books from provinces with variant levels of churchmanship. High church provinces like the Scottish Episcopalians or low church provinces like the Church of Ireland, or the Reformed Episcopal Church, which joined the ACNA and will presumably use the new 2019 BCP (which is absolutely canonical and compliant with Resolution VIII of the 1867 Lambeth conference) alongside its existing BCP, should I think, in a spirit of latitudinarianism, not be evaluated, but rather, we should populate the yellow and red list only with those prayer books which embody and propagate the heresy which is causing so much harm, like the TEC bishop who is about to be tried for refusing gay marriage in his diocese. I am disinclined to list anything published prior to 1950 on either list, because I think both @Stalwart and I could agree that the problems really started after that time, even though we differ slightly on the causation, specifically we are not in accord on the role of Dom Gregory Dix, with just a few extremely compelling exceptions, which all predate the Lambeth accord, and which I further consider to be in part responsible for it, which I would enumerate as: - The Book of Common Order or whatever it was called, that the Puritans of Oliver Cromwell imposed on the Church of England during their tyranny - The proposed Liturgy of Comprehension of 1689 might qualify for the yellow list, despite having some good material, as it was intended to facilitate a union between Anglicans and non-conformists. -The infamous Unitarian BCP modification published by the schismatic King’s Chapel in Boston in several editions, starting in the 1780s - red list, in theory, except the King’s Chapel in leaving the Church of England for the Unitarians, rather than joining one of the legitimate successors in North America (or the legitimate successor; on this point I am inclined to consider the Protestant Episcopal Church and the Methodist Episcopal Church to both have had some degree of legitimacy in this regard in the 1780s, owing to the confusion and what I consider a lack of schismatic intent on the part of Rev. John Wesley, who remained a curate in the Church of England until he reposed). - The proposed American BCP of 1786 would at least be on the yellow list, but I think the red list, in that it diverged radically from the 1662 BCP, the instructions of the Scottish Bishops who ordained Bishop Seabury, the 1789 BCP ultimately adopted, and also the Methodist Sunday Service Book; if memory serves the Trinitarian theology was watered down in this work but not to the same extent as in the King’s Chapel book, but this perhaps belongs on the red list. - Lastly, Benjamin Franklin, who many of us admire, along with a notorious and vile libertine, Sir Thomas Dashwood, proposed a radical abridgement of the BCP, which appears at face value to have been a legitimate proposal, but closer examination suggests it was a nasty farce, given the status of Dashwood as a “notorious evil-liver”. You might judge for yourself if this belongs on the Red List; the text is readily available online, but I refuse to link to it. These books, I believe, combined with the special needs of missionaries operating in South Africa and other regions, including places outside of British dominion, led to the adoption of Resolution VIII; the experience in South Africa, America and even Ireland, which since 1666 until 1802 had its own BCP edition, indicated that there was a need for more than one, but the aforementioned books, which ranged from well-intentioned in the case of the Liturgy of Comprehension, to evil, in the case of Cromwell and his Puritans, the schismatic Unitarians of King’s Chapel, and the Franklin-Dashwood horror, and the near disaster of the 1786 proposed book in America, led to the need for this resolution. ~ I would note the Eastern churches allow variations of rites and usages, with two Eastern Orthodox churches having a Western Rite, the Russian Orthodox church maintaining the Russian Old Rite (after the disastrous schism caused by Patriarch Nikhon’s attempt to change the liturgy of the entire church in the 17th century, to make it closer to the current form of the Greek liturgy, unaware that the Russian liturgy was not in error but merely represented an earlier recension, from long before the fall of Constantinople; this resulted in a horrible and bloody schism which is the worst attrocity that ever happened within the Eastern Orthodox communion) in the past thousand years; also, monasteries have the freedom to develop their own variant uses, in terms of the timing and arrangement of services, and this to some extent extends to parishes, cathedrals and dioceses. And each of the Oriental Orthodox churches has its own liturgical rite. Most of these churches used to have two liturgies, a Cathedral Use, and a Monastic Use, with small parishes tending to split the difference as it were, but in most the Cathedral Use became extinct, except in the Assyrian church where the Monastic Use became extinct as the genocide of most members of the Church of the East; all of them outside of India, Persia, and Mesopotamia, by the evil Tamerlane in the 12th century, resulted in the demise of monasticism in that church, although there was a recent attempt to revive it. So the Assyrian Church (and its Roman Catholic offshoots, the Syro Malabar Catholics in India, and the Chaldeans, who unlike the Assyrians mainly speak Arabic in the vernacular rather than an Aramaic dialect), has just Matins, Vespers and Compline, unlike the long divine office of the other Eastern churches; their liturgy is quite beautiful and I am a fan of it.