Sienna Miller in Robin Hood-style tax campaign

British actress Sienna Miller has become the face of a new Robin Hood-style drive to tax the banking system.

The ad campaign for Oxfam witnesses the 28-year-old Miller donning a green mask.

"It is time for the Government to be like Robin Hood. This could be the world's first popular tax," the Daily Star quoted the charity's Max Lawson, as saying.