One of the witnesses told London's Southwark Crown Court she was "shocked" when Harris allegedly grabbed her breast and touched her bottom when she was 15.
The youngster, then a keen artist, went to shake the TV star's hand but Harris said "give us a hug". Speaking via video-link, the woman, who has not been named, told the jury: "He put his right hand on my left breast and through my shirt. He put his other hand on my right butt cheek. It was very deliberate."
She recalled pulling away and rejoining the crowd.When her mother asked what was wrong, the teenager replied that he was "a dirty old man", she recalled.
Her mother also claimed Harris sexually assaulted her that day, saying she felt him rubbing his groin against her buttocks as he stood behind her.
The mother, who was also giving evidence by videolink, said she responded by treading on his foot and telling him "You are a disgusting creature."
The mother told the court his expression switched from "smiling and friendly" to an "almost sneer".
Harris, 84, is accused of 12 counts of indecent assault between 1968 and 1986, all of which he denies.The hearing was adjourned until today.