of commons sat on a saturday on some momentous occasions. at the time of the suez crisis, the time of the suez crisis, the outbreak of world war ii, the outbreak of world war ii, the falklands invasion, so that gives you a sense of the magnitude of what is happening this weekend and the beginning of an extended period of national mourning. during her long reign, the queen was served by 15 prime ministers — 11 conservative and four labour — from winston churchill to liz truss. our political editor chris mason looks back at the premiers who were in office for the seven decades of the queen's reign. fanfare the state opening of parliament — pageantry, tradition, continuity. the connection between the head of state and democracy. as a constitutional monarch, queen elizabeth could not direct government policy. when mps are summoned to attend the royal speech, the door to the commons