Rod Stewart is not the only poster-boy in his family: the singer’s son Alastair is starring in an advertising campaign in Italy — at the age of just 16. ‘My little brother has his own billboard in Milan,’ gushes his half-sister, Ruby Stewart, 35, after seeing huge images of him plastered all over the world’s fashion capital. Alastair, whose mother is Sir Rod’s wife Penny Lancaster, 51, signed the deal with luxury clothing label Palm Angels.