Some readers (but not all) will remember an Anglicanism in which kneeling was the done thing. The bidding "Let us pray" was instantly and easily understood as an instruction to kneel, and we did. The opening prayers, the Collect, the intercessory prayers (aka "Prayer for the Church Militant"), the whole of the Thanksgiving and Consecration...if in doubt, we knelt.
One of the messages of the liturgical movement that hit the Church in the second half of the twentieth century was that we had been kneeling a bit too much. It was true. The one-sided emphasis on penitence and submission found in much Anglican liturgy was one of those camels we had swallowed from the Medieval Church while straining at sacrificial gnats. The ethos of Christian communal action implied in the New Testament, and lived out in the ancient Church, was less focussed on individual breast-beating than on the collective celebration of God's grace.
The resulting message had one startling central theme: stand up! We had been used to standing only for singing - presumably for practical reasons related to our diaphragms - as well as for the Gloria, the Gospel, and the Creed. These had left a clue behind about the meaning of such a posture. We rediscovered through the sixties the fairly natural coherence between a theology emphasizing the victory of the Resurrection and the liturgical norm of standing. The new texts and orders that were introduced around the Anglican world - Series I-III, Australia '69, '77 etc, A Liturgy for Africa - all implied or stated their alignment with such different understandings of posture.
Of course it was not all about standing. Each of standing, sitting and kneeling had a place in this revised set of understandings about how our bodies reflect our belief. Standing was for corporate prayer, including prayers of intercession and the Great Thanksgiving. Kneeling was only for specifically penitential or reflective and personal elements, such as private prayer and the corporate confession of sin. Sitting was for readings and sermon only, aside from waiting before and after the liturgy.
This was, however, an incomplete revolution. Even where the liturgical movement took deep hold, there was hesitation, or appropriate variation, about some specifics. Many have remained deeply connected to kneeling to receive Communion, for instance. While some clergy were being actively and carefully taught such understandings of the new liturgies, others were less well trained. And those who had become liturgical-movement purists were not thereby necessarily good educators or effective pastors.
The result is a mixed bag. In the Diocese of Melbourne, Australia, where Percy has recent and decades-old experience, the basic news is of back-sliding and mess. Where in the 1980s parishes of progressive Catholic mood were standing more and kneeling less, what is most striking is how often they are sitting. Without sufficient education or leadership, sitting has become a norm for corporate prayer of intercession in particular. There is no good reason for this at all, but a perfectly reasonable explanation: sitting is the flaccid via media for people no longer sure whether or stand or kneel, or why.
A related phenomenon is the disconnect between the posture of ministers and that of congregation. It is increasingly common that at times when kneeling might still be expected or encouraged, ministers actually remain standing. Example is, as always, a powerful teacher; where ministers do not kneel, people see little point.
Sitting does have its place, we have acknowledged. And there may be circumstances where that place is larger - where, for instance, the liturgy is celebrated with a more-than-usual emphasis on the meditative or reflective, as in the ethos connected with the community of Taizé. Yet otherwise Percy suggests sitting is, in the tradition of the Church catholic, intended for listening and waiting.
Liturgy is based on the idea that the physical disposition of objects, space and our own bodies actually does matter. There may be different specific opinions about posture, but the present indifference and confusion evident in the Australian Anglican Church, and some other branches of the Communion, is not a matter for celebration.