Yes, it is 'after Easter'

God's singu­lar bounty hath advanced some days to a superlative bright­ness.

On Easter Day I quoted from a Restoration era Easter sermon by John Torbuck, part of a collection of his sermons for feast days under the title Extraordinary Dayes.  In the preface to the collection, Torbuck defended the practice of observing festival days on the basis that God "hath made some days twice" through some signal and pe­culiar mercy".  Such, he says, "are the Festivals of Christs Incarna­tion, Resurrection, Ascensi­on, &c.". 

He notes that such "days above days" are grounded in "Articles of our Creed".  These days, in other words, set before us the redemptive events which have secured our salvation.  This is why these days have "a superlative brightness".

Torbuck's account of the festival days is suggestive of why it is good liturgical practice to describe the Sundays of Eastertide, contrary to conventional contemporary Anglican practice, as 'after Easter'.  To term these Sundays as 'after Easter' embodies the recognition that the Easter proclamation and the Church's faith in the Lord's Resurrection are grounded not merely in the experience of the first disciples but, rather, in a - the - salvific event.

The phrase 'after Easter', then, centres the Church's Easter proclamation on the event of the Resurrection.  As Rowan Williams stated in Resurrection: Interpreting the Easter Gospel, reasserting the significance of the empty Tomb amidst the theological confusion afflicting the Church of the England in the early 1980s:

And for all four Gospels, the story which identifies the ultimate source of this disorientation [i.e. amongst the witnesses to the Resurrection] is that of the empty tomb.  This, at least, provides a clear basis for what is on any other showing very hard to explain, the primitive confession that Jesus was raised 'on the third day': the process of appropriating the Easter gospel has a definite, even dateable beginning ...

The story as it stands also provides a very clear ground for the primitive sense of the resurrection gospel as a message from outside ... 

Something must have provided a first stimulus and, more importantly, a structure of presuppositions within which subsequent experiences could be organized.  The empty tomb tradition proposes just such a stimulus and structure.

... we do well never to forget that the object and ground of the community's faith is not its own life, but that to which its life is an answer: the 'word from beyond', the message from the tomb.

By contrast, suggesting an equality between Easter Day and the Sundays of the Easter Season e.g. 'The Second Sunday of Easter', can be taken to imply an equality between the event of the Resurrection and the apostolic experience of encountering the Risen Lord.  This, we might suggest, runs contrary to Paul's creedal affirmation in which "and that he rose again the third day according to the scriptures" stands apart from "And that he was seen of Cephas, then of the twelve".  

Likewise the Church's Creeds each proclaim not the experience of those encounters but the source of Easter faith, the empty tomb:

The third day he rose again from the dead (Apostles' Creed);

And the third day he rose again according to the Scriptures (Nicene Creed);

rose again the third day from the dead (Athanasian Creed).

As Williams states, the fact that the apostolic community assembled on the first day of the week indicates "that 'the third day' meant exactly what it said":

There is a definable beginning to the process of resurrection encounter, and it is the discovery of the absence of Jesus' corpse.

One way of giving liturgical expression to this - to the foundational nature of 'the third day' for the Church's proclamation of the Risen Lord - is order the Sundays of the Easter season as 'after Easter'.  That is, as dependent upon and flowing from Easter Day and the event of the Lord's Resurrection, witnessed to by the empty Tomb 'on the third day'.  To use Torbuck's phrase, this recognises the "superlative brightness" of Easter Day.  The brightness of the Sundays after Easter is entirely derivative, just as the apostolic experiences of encountering the Risen Lord entirely derive from the saving truth that on 'the third day he rose again from the dead'.