Billy Wilson was a council housing official who appears in Series 1. He had known Frank as a teenager, and claimed to have once found a home for his mother. It was also implied that Wilson had once helped Frank and his family move from their former address in Bishops Grove to Windsor Gardens in Chatsworth to escape creditors, three years before the events of Series 1. When creditors found out where Frank was residing (due to "using his full name somewhere" as Lip guessed), Wilson started investigating the circumstances of the Gallagher household.
Having to maintain that Frank still lived at the house, when in fact he was living at Sheila's, proved tricky however. Frank told Billy which bedroom was his, forgetting that since his move the room had been given a make over and turned into Debbie's room, giving the lie away.
Due to bailiffs trying to track Frank down as mentioned above, Frank took to dressing up as an old woman to safely travel back and forth from the house. Unfortunately, Billy arrived and caught Frank dressed this way, he was disgusted as he thought Frank was dressed this way due to some sort of perversion and saw it as the last straw. He angrily refused to help the family out and left, promising to re house them.
To escape the devoted bailiffs, Norma helped Frank fake his death which required him to pose in a coffin while they visited. However Billy arrived and upon seeing Frank in the coffin, gave the family his condolences and became very emotional. Crying, he recited a poem over Frank's "corpse" and promised to help the family with their housing problem, completely fooled by Frank playing dead.