DAME Maggie Smith got the shock of her life when she found out she would be sharing the London stage with her actor son, because she had no idea he had even auditioned. The veteran Harry Potter actress is starring in West End production THE LADY FROM DUBUQUE and was ecstatic, and surprised, to learn son CHRIS LARKIN had won a leading role. Smith, 73, says, "I had no idea he'd auditioned, and I got the shock of my life when the director, ANTHONY PAGE, rang me from New York about it. "I hope he's going to be good."