A question that can only be answered by one of Her Madge's servants like me
http://news.bbc.co.uk/1/hi/uk_politics/81909.stm
The 'rod' is what gives him his title - Gentleman Usher of the Black Rod. It is more like a fancy long, slender walking cane than a staff - it is made of ebony topped with a Lion's head. He has to tap it on the door of the Commons three times before they will let him in - after having already slammed it in his face of course.
The State Opening is worth watching for quirky old things and posts such as The Cap Of Maintenance, The Earl Marshall, The Sword Of State - all ancient symbols.
Nice image below:
http://www.parliament.uk/about/image...e/blackrod.cfm