Princess Kate Racing William & Harry For A Good Cause Is Royal Perfection .
The Duchess of Cambridge took part in a relay race along with Prince William and Prince Harry overnight to support their charity Heads Together.
The three were joined by about 150 other runners who are training for the London Marathon at Queen Elizabeth Olympic Park in east London.
Although she was suitably dressed for the occasion in jogging bottoms and trainers – the Duchess was beaten by both William and Harry with Harry beating his older brother.
Athletes Iwan Thomas and Paula Radcliffe and presenter Sian Williams were also at the event.
Heads Together is a charity which is backed by the royals and aims to promote mental well-being in young people.