Q. I may be wrong, but I think that, at a Requiem Mass in England on some State occasion the late King Edward VII and his wife, as Duke and Duchess of York, attended and knelt in the Sanctuary.
A. The case concerned King Edward VII and Queen Alexandra, when they were actually occupants of the British Throne. It was in 1908. News had come to England of the tragic death of the King of Portugal. As Portugal was England's ally, a special memorial service was arranged in St. Paul's Anglican Cathedral, which the King and Queen were expected to attend in their State capacity. But King Edward VII declared that he would attend in state the Solemn Requiem Mass in the Portuguese Embassy Church of St. James.
He did so, and was "received in State" by the Catholic Archbishop of Westminster, and the King and Queen were conducted through the church to the Sanctuary and given a place there, apart from all the Ministers and Ambassadors of various countries, who occupied the front seats in the body of the church. Horrified by King Edward VII's presence at the Mass, the Protestant Alliance publicly protested afterwards that, by the William of Orange Act of Parliament, of 1689, the King forfeits the Throne by any act of communion with the Church of Rome, and the people of England are thereby absolved of their allegiance.
But the public was quite unimpressed by the protest. and just went on with its allegiance as usual.
The Malayan Catholic News, January 25, 1959, page 4