William "Billy" Brown was the son of Cilla Brown and half-brother of Fiz and Chesney Brown.
A soldier, he served in Iraq where was posted as missing but turned up after being on a bender with some mates which earned him fourteen days in a military prison.
While still serving in the military in October 2005, Billy accepted a request from his mother to be her partner Les Battersby's best man at their wedding later that month. At the same time Les had already offered the position to Kirk Sutherland. Cilla was initially adamant that Billy receive the honour, but relented on the condition that Kirk perform twelve Herculean tasks to prove himself best man material. His tasks included: slaying the Nemean lion - getting Schmeichel's toy off him, capturing the girdle of the Queen of the Amazons - obtaining one of Blanche Hunt's corsets, and capturing the Erymanthian Boar - stealing one of Keith Appleyard's pigs. When Kirk failed to get his hands on one of the pigs, instead trying to use Roy Cropper as a substitute "bore", Cilla was unimpressed and dismissed him from best man duties.
The night before the wedding, Cilla brought a young man home but the pair were interrupted when a drunk Les arrived back. Cilla was able to convince Les that the man was Billy, and the next day at the wedding Billy was forced to play along with the deception in order to cover for his mother's lies. Due to the wedding having not been agreed upon by St. Judes Church vicar Reverend Michael, fake vicar Father Abraham rushed through the ceremony as quickly as possible and as Rev Michael returned, Billy was forced to breach a window and later made his getaway in a limo with the rest of his family before the real vicar could apprehend them.
At the reception, Billy offered Kirk the opportunity to make the best man's speech.