Sid Humphrey is a mild mannered old type gentleman who is the love interest of prisoner Lizzie Birdsworth. She is paroled and get to live with Sid, but when Sid dies Lizzie burns down his house so that his evil son will not get the money for the house. Lizzie gets sent back to Wentworth on charges of burning down the house.
First introduced as a prison handyman, a neighbour of Colleen Powell's who comes to Wentworth to fix the TV. He becomes friendly with Lizzie and a touching little courtship is played out between them. Colleen finds Sid unconscious at home after a stroke (174). Lizzie visits him in hospital and is dismayed by his condition. Though not seen for a while after this, Sid continues to be mentioned - he provides the pollen Evelyn Randall uses to poison the women and when Lizzie escapes to visit him in his nursing home, she finds he has gone to live with his son Gordon. When Lizzie finds out that Sid has returned to his own home, she gets permission to visit him there (212). Their romance continues again and they eventually become engaged. Sid's son objects to the marriage because he thinks Lizzie is only after the house and sure enough after Sid's death (222) Lizzie does get it, but burns it down. A framed photo of Sid is Lizzie's prized possession for a long time afterwards.