Lady Louise Windsor was in stitches as the Duchess of Edinburgh played a drinking game in a carriage.
Sophie, 59, held a wine glass in her teeth while carriage driving, as her daughter Louise, 20, laughed in hysterics.
The duchess tried to down her drink while carriage driving, as Louise, a student at the University of St Andrews, was visually very impressed.
Sophie had to put her glass down at the next stop, but unfortunately, she missed, which left Louise and Prince Edward, 60, in stitches.
The mother-of-two wore a blue velvet coat from Laurie & Jules which she paired with a hat from Jane Taylor London.
The drinking game took place at an event on the Sandringham estate in Norfolk.
Lady Louise and the Duchess of Edinburgh are both keen carriage drivers
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The 59-year-old skilfully guided her horse and carriage up to a wine glass perched on a post then drank the sparkling water as she drove along.
But she did not manage to finish the drink in time, with several snaps showing her cheeks puffed out as she quickly tried to down it.
As a result, Sophie missed the second post where she was supposed to put the glass down.
Quickly realising her mistake, Sophie tried to reverse back, but when this did not work, she held the glass between her teeth and continued.
Lady Louise was in stitches while the Duchess of Edinburgh played a drinking game
PA
Edward, who was dressed casually in a white polo shirt and straw hat, filmed the entire attempt on his phone while Louise watched beside him.
She found her mothers’s attempt hilarious and was captured pointing and laughing at her mother.
Earlier in the day, Louise competed in events at the Sandringham Horse Driving Trials.
It was the first time she had competed at the Sandringham trials, invented by her grandfather, the late Prince Philip, who encouraged her to take up the sport.
Sophie, Duchess of Edinburgh drinking at the Royal Windsor Horse Show
PA
Lady Louise and the Duchess of Edinburgh shielding from the rain at Trooping the Colour
PA
Louise, who is currently studying English Literature, made her eventing debut three years ago.
The Sandringham trials were started in 1982 by the former Duke of Edinburgh.
Philip wanted to bring one of his favourite sports to Norfolk and it always takes place the weekend after Royal Ascot.
