The Duchess of Cambridge’s uncle has admitted punching his wife in the face and knocking her to the ground after a drunken row.
Gary Goldsmith, 52, attacked Julie-Ann Goldsmith outside their home in Wimpole Street, central London, in the early hours of 13 October.
Westminster Magistrates’ Court heard the pair had argued in the back of a taxi before he threw a “left hook”.
Goldsmith pleaded guilty to one count of assault by beating.
Prosecutor Kate Shilton told the court the couple’s taxi driver saw Mrs Goldsmith slap her husband in the face before he retaliated as they got home after a charity event.
She said Mrs Goldsmith had “fallen backwards” after the punch and the taxi driver believed she had been knocked unconscious.
Mrs Goldsmith remained on the floor with eyes closed for about 15 seconds before she woke and staggered to her feet and crying, the court heard.
Ms Shilton said Goldsmith appeared to be “panicked” and when the taxi driver challenged him over his actions, he became aggressive.
The court was told Mrs Goldsmith then asked the taxi driver to call the police.
When at the police station Goldsmith said he had pushed his wife hard but denied hitting her. The court heard he was apologetic for his actions.
Ahead of sentencing, which will take place on 21 November, chief magistrate Emma Arbuthnot said she was “excluding custody and looking at a community order”.
“But I am really looking at how to protect this lady from this man,” she said.
Mr Goldsmith is the younger brother of Carole Middleton and attended the weddings of both her daughters – the Duchess of Cambridge and Pippa Middleton.