article: It will be the first public engagement for maritime expert Jeffrey Mountevans, who is the 688th mayor to fill the position, representing the city in financial and business matters across the world. Since 1215 every newly-elected Lord Mayor has to leave the City of London and travel through to Westminster to swear loyalty to the Crown. The procession has moved from river barges, or floats, to horseback and then to a parade surrounding the State Coach. Hundreds of thousands of spectators join the Lord Mayor on the streets of London in what is said to be the world's largest un-rehearsed parade. This year's pageant is set to be 7,000 strong, including featuring more than 170 horses, 140 vehicles, Taiko drummers, vintage steamrollers, tractors, fire engines, armoured vehicles, the Batmobile, a replica of Noah's Ark and a tank. To celebrate the show's 800th birthday, the St Mary-le-Bow church bells will ring out a special 800-change at 12:00 GMT. Artwork for this year's show was created by British pop artist Sir Peter Blake, who also drew the album cover for the Beatles' Sgt Pepper's Lonely Hearts Club Band.
summary: A historic carnival will mark the 800th anniversary of the role of Lord Mayor of the City of London next Saturday.