Name this famous celeripedean!

A snap of a page from an autobiography (seeing as it's world book day) written by a celeripedean. I've layered it with some colour and texture just for fun. Taken for DDW's March challenge: celeripedean, meaning swift-footed.


Who is this?

Clues: this very famous swift-footed male was just 5 years old in this picture, taken circa 1904; he made movies; his celeripedean sister went on to be known as Lady Cavendish, but what was his name? I mean super-famous!

Answer:
https://farm4.staticflickr.com/3478/13006149294_1bb50af566_c.jpg