English brides lead the processional down the aisle, with her bridesmaids in tow unescorted by ushers, who stand at the front of the church with the groom. The couple has selected the 32-person Choir of Westminster Abbey, the Chapel Royal Choir, the 39 musicians of the London Chamber orchestra, and the Central Band of the Royal Air Force to perform various selections, which royal officials say will include well-known hymns and choral works, as well as some specially-commissioned pieces. Some royal wedding staples have been Mendelssohn's Wedding March, the hymn The Lord's My Shepherd, and Widor's Toccata from Organ Symphony No. 5, which was the recessional music at Edward and Sophie's wedding. (Official recordings of Will and Kate's music will be available on iTunes May 5.) The ceremony itself will be divided between three officiants: the Dean of Westminster conducting the service, the Archbishop of Canterbury presiding over the vows, and the Bishop of London giving the address. Will and Kate will likely exchange traditional vows, with one possible exception: Back in 1999, Sophie, Countess of Wessex, caused an uproar for promising to "honour, cherish and obey" Prince Edward, a public relations nightmare the newest royal couple might want to avoid repeating.