Jimmy's family

My friend lives in London. His name is Jimmy. He often writes to me and I know very much about his family.
Jimmy has a sister. Her name is Betty. She is two years younger then Jimmy. Their parents are young. Their father is Mr.Johnson, he is a doctor. The children often call him Daddy. Their mother is Mrs.Johnson, she is a doctor,too. The children call her Mummy.
Jimmy's grandfather and grandmother are not old, they live on a farm near the sea. Jimmy and Betty like to stay at the farm in summer.
Jimmy is a good swimmer,too. He can swim in the sea very well. Sometimes the children help their grandfather and grandmother to work in the garden. They have a very good time at the farm in summer.