When the Sovereign drives in State to open or prorogue Parliament.
The first time he used it was when he travelled to Westminster to open Parliament on 25 November 1762.
Each year the queen, as head of state, wears a formal evening dress under her robes when she opens Parliament.
On 16 February 1909, King Edward officially opened Parliament for the coming year.
"Might I ask-have all the arrangements been made for the Queen to open Parliament?"
The Queen opens and closes Parliament, which is led by her prime minister.
On July 22 the king opened Parliament.
The Queen opens Parliament by reading a political program, but no one asks whether she believes it or even understands it.
Her Majesty has opened Parliament on 58 occasions and has only missed two during her reign.
Originally known as the Annual Message, it mimics the "speech from the throne" that opens Parliament.
