Finding myself reading Abbot Gasquet to chase down something he wrote about the state of Catholics in England in the eighteenth century (paying double taxes, at the mercy of non-Catholic neighbours who could demand their property etc) which reminded me of the place of Christians under Islamic rule, forced to pay the jizya, and forever second-class citizens at the whim of their neighbours, I came across something odd; that following the 1778 Relief Act, the Vicars Apostolic had inserted the name of the King into the Canon of the Mass (he is precise enough to cite a document signed on 4 June 1778).
Before Pius V's Tridentine Missal, a prayer for the Monarch had been part of the Canon since at least the fourth century, coming immediately after the prayers for the Pope and the Bishop. This was removed from the 1572 Missal, though it was retained as a privilege in countries with Catholic monarchs, and at the time the Catholic Encyclopaedia was published in 1911, Franz Josef was prayed for as Emperor in Austria, and as King in Hungary (and of course all rites and uses other than the Roman Rite remained unchanged).
But assuming Abbot Gasquet has got this right, the addition of George III to the Canon seems to imply three things that I would not have imagined possible: that such a change might be made so late in the eighteenth century without any perceived need for the sanction of Rome even though the Monarch was far from Catholic; that the Vicars Apostolic, who were administrators of districts, not Bishops in their own sees, felt they had the authority to do this; and that it should have lapsed before the restoration of the Hierarchy without any significant discussion which might have left an obvious trace to this day.
Does anybody have any further information on this?