Sienna Miller's sister Savannah has told her to take some time out from partying

The 26-year-old fashion designer is apparently worried her younger sibling is too caught up in the busy celebrity world.

"Savannah and Sienna have always been close, even though they are totally different people," a friend told the Sun. "Savannah is laid-back and not into any trendy London scene.

"She feels her sister has been caught up in a whirlwind of media attention ever since she and Jude Law broke up."

The responsible Miller has now decided to step in, insisting Sienna join her for a quiet break at her West country home.

"Because Sienna has been racing around the world concentrating on her career, they haven't had any bonding time since they were in Mexico with their mother Jo at Christmas," continued the source. "So Savannah told Sienna in no uncertain terms that she was expected down in Cornwall."