Paradise End

Paradise End by Elizabeth Laird, author of The Fastest Boy in the World, is the story of an unlikely friendship between two girls who both long for a different life. Carly often finds herself gazing through the gates of Paradise End. She fantasizes about discovering that she was swapped at birth, and is in fact the rightful owner of the beautiful, empty mansion. She longs to escape the three-bedroom semi she shares with her ordinary parents, her revolting brother and annoying sister, to go and live in the palatial luxury of the fascinating house.
Then she meets Tia, the daughter of the new tenant of Paradise End, and Carly begins to realize that life behind the impressive pillars and long, elegant windows isn't anything like her dream.