Harry Potter star, Jessie Cave, who has announced her pregnancy on Instagram.This baby will be the third for Jessie and her boyfriend, comedian and musician Alfie Brown, who already share two children – Donnie and Margot.The actress and artist, known for her role as Ron Weasley's clingy girlfriend Lavender Brown in the Harry Potter films, announced the news with a picture of her growing bump and the hilarious caption: "Oops I did it again".