Hello
The date for the Coronation of King Edward VII was originally scheduled for 26th June 1902.
The day before the King became ill with appendicitis and need surgery.
A new date was chosen in August, but the King was still quite ill and there were doubts that he would be able to walk to the throne. Although he did get there he was in considerable pain. In fact the whole service was a shambles as the Bishop got the words wrong, put the crown on backwards and many guests who had come for the June event could not attend the August date.
As for Souvenirs like your Coin, 1000's had already been made with the original date - mugs, tins, flags, etc etc.