THE Duchess of Cambridge gave her husband, Prince William, and brother-in-law, Prince Harry, a run for their money on sunday as the trio took to the marathon training track to show their support for participants of this year's Virgin Money London Marathon on behalf of their charity Heads Together, the official charity of this year's event. The 100m sprint took place at the Queen Elizabeth Olympic Park in London, and saw the royal ambassadors joined by three-time marathon winner Paula Radcliffe. While the Duchess came in last, after Prince Harry and Prince William (who took first and second place respectively), there were smiles all round. Kensington Palace reported the events of the day as they unfolded on its Twitter account, highlighting the reason that the royals were there. "The Duke and Duchess, and Prince Harry, are working to eliminate the stigma around mental health with #HeadsTogether," it tweeted, followed by "Their Royal Highnesses are championing the #HeadsTogether campaign to urge people to talk about mental health."