Composer: Charles-Marie Widor
If you want to style your wedding with a royal flavor, an absolute must is the inclusion of French organist and composer Charles-Marie Widor's Toccata as your recessional. It has been the choice of at least three Danish royal weddings, and five British ones, most recently the wedding of Prince William and Kate Middleton in 2011.
The Toccata is the final movement of his Fifth Symphony for Organ and easily his most famous work. It is utterly suited for a grand cathedral with a wizard of an organist, and the merits and flaws of the numerous recordings are hotly debated by organists with specific preferences for performance speed, articulation, etc. At any rate, concluding your wedding ceremony with this triumphant piece would be an exhilarating segue into the remaining celebration of your wedding day.