This was not an extraordinary event. The Church of England is the Establish Church of the Kingdom and the preacher was one of the most renown Churchmen of his era. He was only the second person in the History of Oxford to achieve a "Double First" and was the Professor of Poetry.
What was exceptional was the content of the sermon. He, against all precedent since the 17th century, preached a sermon with content.
The first two paragraphs of the Sermon follows:
On public occasions, such as the present, the minds of Christians naturally revert to that portion of Holy Scripture, which exhibits to us the will of the Sovereign of the world in more immediate relation to the civil and national conduct of mankind. We naturally turn to the Old Testament, when public duties, public errors, and public dangers, are in question. And what in such cases is natural and obvious, is sure to be more or less right and reasonable. Unquestionably it is mistaken theology, which would debar Christian nations and statesmen from the instruction afforded by the Jewish Scriptures, under a notion, that the circumstances of that people were altogether peculiar and unique, and therefore irrelevant to every other case. True, there is hazard of misapplication, as there is whenever men teach by example. There is peculiar hazard, from the sacredness and delicacy of the subject; since dealing with things supernatural and miraculous as if they were ordinary human precedents, would be not only unwise, but profane. But these hazards are more than counterbalanced by the absolute certainty, peculiar to this history, that what is there commended was right, and what is there blamed, wrong. And they would be effectually obviated, if men would be careful to keep in view this caution:—suggested everywhere, if I mistake not, by the manner in which the Old Testament is quoted in the New:—that, as regards reward and punishment, God dealt formerly with the Jewish people in a manner analogous to that in which He deals now, not so much with Christian nations, as with the souls of individual Christians.
Let us only make due allowances for this cardinal point of difference, and we need not surely hesitate to avail ourselves, as the time may require, of those national warnings, which fill the records of the elder Church: the less so, as the discrepancy lies rather in what is revealed of God's providence, than in what is required in the way of human duty. Rewards and punishments may be dispensed, visibly at least, with a less even hand; but what tempers, and what conduct, god will ultimately reward and punish,—this is a point which cannot be changed: for it depends not on our circumstances, but on His essential, unvarying Attributes.
I have ventured on these few general observations, because the impatience with which the world endures any remonstrance on religious grounds, is apt to show itself most daringly, when the Law and the Prophets are appealed to. Without any scruple or ceremony, men give us to understand that they regard the whole as obsolete: thus taking the very opposite ground to that which was preferred by the same class of persons two hundred years ago; but, it may be feared, with much the same purpose and result. Then, the Old Testament was quoted at random for every excess of fanatical pride and cruelty : now, its authority goes for nothing, however clear and striking the analogies may be, which appear to warrant us in referring to it. The two extremes, as usual, meet ; and in this very remarkable point : that they both avail themselves of the supernatural parts of the Jewish revelation to turn away attention from that, which they, of course, most dread and dislike in it: its authoritative confirmation of the plain dictates of conscience in matters of civil wisdom and duty.
The entire text is here.
This is generally seen as the beginning of the Oxford Movement. It would trigger the Tracts for the Times under the editorship of John H. Newman and caused a stir that lasts to this day. The Movement was defined by it's belief in the catholic heritage of the Church of England and her daughter churches, it's adherence to the Church Fathers and a distrust of evangelicals and "enthusiasts" alike. They were dedicated to expanding the missionary impulse of the Church and to reenergize the moribund Establishment. The current shape of the Book of Common Prayer for the Episcopal Church relates to the work of the Movement, as do the Prayer Books of most of the Anglican communion.
In light of the anniversary and the upcoming Lambeth Conference (another piece of the legacy of the Movement), many are spending an hour in prayer for the continuance of the Movement and the health of the Anglican Communion.