Duchess of Edinburgh leaves Prince Edward and Lady Louise in hysterics as she fails at drinking game during Sandringham Horse Trials

The Duchess of Edinburgh had Prince Edward and Lady Louise in hysterics this weekend when she took part in an unusual challenge while carriage driving.

Sophie, 59, was seen participating in the Sandringham Driving Horse Trials on Saturday while her husband and daughter watched on.

During the event, the royal was challenged to hold a wine glass full of sparkling water between her teeth as she drove along.

The Duchess was then meant to place the glass down at the next stand - but missed the post.

As she attempted to reverse back, Prince Edward , 60, and Lady Louise, 20, were spotted laughing hysterically from the sidelines.

The Duke of Edinburgh was spotted with a large grin on his face and captured the hilarious moment on his phone.

Sophie looked elegant in a navy velvet jacket from Laurie & Jules, sapphire blue netted hat from Jane Taylor London, a chequered white maxi skirt and brown boots.

Sophie's participation in the competition comes after she accepted an invitation to become the President of the Sandringham Horse Driving Trials.

It has a long-standing relationship with the royal family and was founded and presided over from inception by the late Prince Philip.

The Sandringham Horse Driving Trials said they are 'deeply appreciative' that the Duchess has taken on this role.

In a statement, a spokesperson said: 'The Duchess's acceptance marks a continuation of the Royal Family's esteemed association with Sandringham Horse Driving Trials, and we are looking forward to a long relationship with Her Royal Highness.'

Prince Edward was stood shielded from the sun in a straw hat as he donned a relaxed look consisted of a simple white polo shirt and baggy brown trousers.

Meanwhile, Lady Louise looked chic in an oversized navy blue polo shirt which she tucked into camel-coloured trousers, showing off her sophisticated figure.

The St. Andrews University student paired the simple look with some brown leather Chelsea boots and a bright blue belt to tie the look together.

She wore her wavy blonde tresses up in a stylish messy ponytail and went for a natural makeup look today.

She made an impressive debut and managed to bag herself a silver medal in the three-day competition. It is believed her grandfather, Prince Philip, encouraged her to take up the sport.

The family were joined by Lady Louise's friend, Felix da Silva-Clamp , with whom she seems to have formed a strong bond, as they both study at the same university in Scotland.

Felix was driven to the event by the Duchess of Edinburgh, and the two were seen engaging in conversation as they watched the races.