Amongst Black Rod's ceremonial duties, the best known function is the summoning of the House of Commons to the House of Lords at the State Opening of Parliament when the Commons are called to hear the Queen's Speech. This elaborate ritual involves Black Rod walking from the Lords Chamber, through the Central Lobby, down the Commons corridor to the Member's Lobby. As Black Rod crosses the Lobby, the door of the Commons Chamber is slammed in his face. He knocks three times and is then admitted and advances to the Table of the House and summons the Commons who then follow him back to the Lords Chamber.

This picture shows Sir George Mills (1902-1971), Gentleman Usher of the Black Rod 1963-1970, in the chamber of the House of Commons.

The custom of Black Rod knocking three times dates back to 1641, when, as noted in the House of Commons Journal: ‘Mr Maxwell, coming to the House, with a Message, without his Black Rod; and coming in, before he was called in: Exception was taken to both.'