Having downloaded from the Church of England website The Order for the Celebration of Holy Communion also called The Eucharist and The Lord's Supper, according to its latest "Common Worship" formulæ, I now see where many of the elements of the new Ordinariate Mass come from.
For instance, the suggestion to use the 1662 version of the Veni Creator Spiritus as a preparatory prayer in the sacristy might have seemed a rather self-conscious throwback to the Sarum Rite – were it not that the same hymn in the same version is offered as the first text to be prayed in A Form of Preparation for private or public use before, or as part of, the Communion service.
Leaving aside the prayers at the foot of the altar – which (sans Confiteor) appeared in the 1928 Proposed BCP, and (including modified Confiteor) in the 1970 Scottish Episcopalian Liturgy – much of the Ordinariate Mass order of service, down to the prayers of intercession after the Creed, corresponds to the modern Church of England "Order One in Traditional Language" combined with "Order Two" (which is in traditional language also): Anglicans still allow the use of such hieratic diction without carping criticism thereof.
For example, I was interested to find that, as an alternative intercession, the 1662 Prayer for All Conditions of Men, slightly modified, was suggested for use in the Ordinariate Mass – but I am far less surprised to find it there, now I know that the same prayer, with the same modifications, is found in these "Common Worship" provisions.
What of provision for the use of the modern Roman Rite offertory prayers, as "Form II" in the Ordinariate Mass? Well, the two berakoth prescribed for use at the presentation of the hosts and mixed chalice are present, in a version minimally variant from the old ICEL paraphrase, in the "Common Worship" compendium; just as they were in the 1970 Scottish Episcopalian Liturgy.
But most notably – and to many, most strangely – the Ordinariate Mass does not take up a Catholicised Anglican Eucharistic Prayer; instead, alongside the Roman Canon, which may always be used, and must be used on Sundays and feasts (would that the like rule in the modern Roman Missal recommending either it or E.P. III for Sundays and feasts were obligatory, not merely a suggestion), one finds, in "traditional language", Eucharistic Prayer II.
The reason for this I have discovered: amongst the many Eucharistic Prayers appointed in the Church of England's "Common Worship", Prayer B is transparently a reediting of Eucharistic Prayer II, excluding its intercessions for the Church and the faithful departed. Hence, as Eucharistic Prayer II is both the most commonly used Eucharistic Prayer of the modern Roman Rite, and the one prayer present in recognizable form in both the Roman Missal and "Common Worship", it was adopted for use in the Ordinariate Mass as an option on weekdays, simply being put into traditional language so that it matched the style of the rest of it.
Many of the monuments of Anglican devotion, such as the Prayer of Humble Access (before Communion) and the Prayer of Thanksgiving (after Holy Communion), are of course present in these "Common Worship" Orders; and have passed into Catholic use. Similarly, the Anglican forms include a modified form of Ecce Agnus Dei and Domine, non sum dignus. That curious phrase appointed in the Ordinariate Mass for use at the fraction, "Alleluia. Christ our passover is sacrificed for us. – Therefore let us keep the feast. Alleluia." is found (as an alternative invitation to Holy Communion) in these Anglican forms.
The Ordinariate Mass is most distinguished from "Common Worship", and from the modern Roman Rite, by its inclusion of features specific to the traditional Roman Rite, as taken over into Anglo-Catholic use in the Anglican Missal tradition: the Tridentine prayers at the foot of the altar and Tridentine offertory prayers, the immemorial form of the embolism after the Lord's Prayer (a valuable text, including as it does explicit mention of the intercession of Our Lady and the Saints, even if the Eucharistic Prayer used does not), and the Last Gospel.
Features common to both forms of the one Roman Rite, such as the Orate fratres, the Secret or Prayer over the oblata, and above all the venerable Roman Canon, the Eucharistic Prayer of the Western Church for at least 1600 years, complete the Ordinariate Mass.