The placement of the Our Father. . .

Perhaps there was no set placement of the Our Father within the Canon of the West or a diversity of placements both before and after the Words of Institution.  We do not have a plethora of sacramentary information to detail any assertion one way or another.  But that all changed in the time of Pope Gregory I (c. 540 - 12 March 604), commonly known as Saint Gregory, who left his imprint upon the Church in many pastoral ways.  This is something of a surprise for someone who had been Rome's "mayor" at 30 before entering a Benedictine monastery.  Perhaps it was his monastic background which enabled him to offer what are widely held as great improvements upon the state of the liturgy and church music. Gregorian chant is named in his honor and it is not too much to offer him this praise.   In addition, Gregory is the author of many of the prayers  within the liturgy, including the Christmas Preface and the Preface of Easter and the Ascension.   But he is also receives the credit for a uniform placement of the “Our Father” after the Canon in the Mass.  Indeed, he found it impossible to consider that any words of man would follow or be prayed prior to the reception of the Lord's body and blood.

Pius Parsch, noted liturgical scholar, puts it this way:

According to the great Pope [Gregory the Great], the Our Father is not so much a preparation for the Holy Banquet, as a consecration prayer, in the ancient sense of a prayer for the offering of the sacrifice. For this reason, in the Roman liturgy, it is recited by the celebrant alone, whereas in the Greek liturgy it is considered the table prayer of the congregation, who therefore recite it in common as a family about to approach the sacred banquet. According to Gregory I, therefore, the Our Father should be considered the completion of the Canon, corresponding to the Preface, in such wise that the Preface and the Our Father mark the beginning and the end of the Canon, which is recited in mystical silence. 

Oddly enough, The Lutheran Hymnal violated the order (along with other Lutheran Church Orders based upon 16th century Lutheran practice) but kept the other part of Gregory's preference:  that the people did not say or sing the Our Father but that it was solely the priest.  When the priest says these words, he is supposed to be staring at the Host (Roman historic practice).  It is a profound moment to have the priest address the prayer to the Father while looking literally at the Son and it is an awesome expression of the mystery of the faith for that priest say who art in heaven while Christ is there present in the Eucharist!   Josef Jungmann sees “the people say[ing] the Our Father along with the celebrant. It is the people’s Communion prayer.”   It is certainly their pre-communion prayer.  However, when the people "take over" the praying of the Our Father, it does affect the way it is seen as a consecration prayer, along with the Words of Institution, which is a connection long held long before Lutherans made their liturgical adjustments to the order.

In a sermon St. Augustine says:

If perchance, in consequence of human frailty, our thought seized on something indecent, if our tongue spoke something unjust, if our eye was turned to something unseemly, if our ear listened complacently to something unnecessary, it is blotted out by the Lord’s Prayer in the passage: “Forgive us our trespasses,” so that we may approach in peace and so we may not eat or drink what we receive unto judgment.

Lutheran efforts to recover the Eucharistic Prayer over the years have dealt with the placement of the Our Father and left us with two orders as well as two canons.  I must admit that I find it hard to reconcile the two.  It is for me one of the difficulties of constantly switching liturgical settings in LSB -- the canons being so very different and the placement of the Lord's Prayer itself almost opposite.  I wish we had been more careful to make sure that the canons were consistent and the only consistency I think appropriate is to follow the Gregorian convention of the last 1400 plus years which is consistent with the East as well.