Duchess of Cambridge races Prince William and Prince Harry in London Marathon charity sprint

The Duchess of Cambridge showed that the fun is in taking part when she came last place in a charity sprint in the Queen Elizabeth Olympic Park in London.

The Duchess, alongside Prince William and Prince Harry, took part in the 100m run on Sunday (2 February) to promote their Royal Highnesses' new charity initiative Heads Together, which has been chosen as 2017's Virgin Money London marathon charity of the year.

Prince Harry strode into first place when he took part in the royal charity dash, leaving Prince William a doleful second, and the Duchess lagging behind in third place.

The royals then took part in a training session on the park's new London marathon community track, alongside 150 competitors who will be taking part in the gruelling run for the charity initiative.

Once the exercise was over, Prince William addressed the competitors that will be taking part in the marathon on behalf of Heads Together, which hopes to fight the stigma around discussing and treating mental illness.

The runners received advice and encouragement on how they can inspire people to talk about mental health in the build up to the marathon. The Duchess and the Princes, however, intend to leave the 26-mile long slog in the hands of the headband-clad hopefuls who attended the training session.

According to the Heads Together Facebook page, the charity initiative will be "the biggest single project Their Royal Highnesses have undertaken together".

The campaign will support an umbrella of handpicked charities, including Mind, infant charity Best Beginnings and the Anna Freud Centre for Children and Families, which provides training and help for children struggling with mental health conditions.

Virgin Money London Marathon will take place on 23 April, which will mark the 36th year of the long-distance running event.