The Duchess of Cambridge's uncle has been banned from the home he shared with his wife after he admitted knocking her unconscious in a drunken row.

Gary Goldsmith, 52, struck Julie-Ann Goldsmith, 47, with a 'left hook' as they returned home following a charity auction at a private members' club in London in October.

The drunken attack, which unfolded in front of a shocked taxi driver, left Mrs Goldsmith unconscious on the ground and needing hospital treatment, Westminster magistrates were told.

Businessman Goldsmith, estimated to be worth £30million, is the younger brother of the Duchess's mother Carole Middleton and attended the weddings of both Kate and Pippa.

He was bailed today on condition he only attend the couple's home with an appointment. Prosecutors are applying for a restraining order banning him from contacting his wife when he appears at court again next week.

The Duchess of Cambridge's uncle Gary Goldsmith arrives at court before pleading guilty to an assault by beating charge. He attacked his wife after a night out in London

Mr Middleton had tried to get a police caution to avoid court action but prosecutors refused

The couple went to a charity auction before Mrs Goldsmith (pictured, left, today) was hit. They were pictured in this image (right) posted on social media shortly before the incident

Prosecutor Kate Shilton told the court Mrs Goldsmith fell down after her husband threw what was described by their taxi driver, Daniel Shepherd, as a 'left hook'.

She said: 'The argument took place in the back of a taxi. They both got out of the taxi and he [Mr Shepherd] describes Mrs Goldsmith slapping her husband to the face.

'He then describes how Mr Goldsmith punches her hard in the face using a left hook.

'Mrs Goldsmith has then fallen backwards. He says: "She appears to be unconscious, she isn't moving".'

It was previously claimed the pair had argued over Mr Goldsmith's alleged cocaine use. A magistrate said they were 'both very drunk'.

Mrs Goldsmith was knocked to the ground, where she remained with her eyes closed for around 15 seconds before coming to and staggering to her feet, the court heard. She asked the taxi driver to call the police.

Ms Shilton said: 'She [Mrs Goldsmith] then becomes upset, starts crying and uses some railings to assist her.'

After the incident, Goldsmith was described as 'panicked and walking in and out of the house, trying to get her to go back in the house'.

The court was told that, when the taxi driver challenged Goldsmith over his actions, he became aggressive.

Julie-Ann is his fourth wife. He is often referred to as the black sheep of the Middleton family

The attack happened outside the couple's home in central London on October 13

Mrs Goldsmith was knocked unconscious and sat crying after being punched, a witness said

At the police station, Goldsmith told officers he had pushed his wife hard with his left hand, but denied using a hook.

The couple had been at a charity auction at Home House in Portman Square, Marylebone before they clashed.

Mrs Goldsmith was taken to hospital in an ambulance after she was hit, but was later discharged, the court heard.

Earlier in the night, Goldsmith had posted a photo of the couple online revealing that he'd successfully bid to join a 'bucket list' expedition to climb Mount Kilimanjaro.

Goldsmith, who appeared in court today wearing a blue three-piece suit with a bronze-coloured tie and a patterned handkerchief in his breast pocket, admitted one charge of assault by beating today.

The charge carries a maximum penalty of six months' imprisonment but it is believed he will face community service.

Goldsmith met with the probation team after the hearing, for a report to be prepared for next week's hearing.

The couple, pictured previously with Mr Goldsmith's daughter Tallulah, argued in a taxi

Mr Goldsmith is seen with his daughter Tallulah at Pippa Middleton's wedding this year. His fourth wife Julie-Ann was reportedly not invited to the ceremony

Chief Magistrate Emma Arbuthnot said: 'I am excluding custody and looking at a community order. But I am really looking at how to protect this lady from this man.'

Jane Humphryes, QC, defending Goldsmith, said it was accepted that the victim went to hospital but was 'immediately discharged'.

She said: 'We accept entirely that she fell to the floor.

Goldsmith is the brother of the Duchess of Cambridge's mother Carole

'But we submit that she went to the floor rather more readily than she would have done without drink on board.'

Julie-Ann is Goldsmith's fourth wife. He married sales executive Miranda Foote in 1991 before they split and he married second wife Luan, with whom he had a daughter, Tallulah.

After he and Luan divorced, he married Julia Leake following a whirlwind romance.

She left him amid a reported row over his drug use and he later met and married Julie-Ann.

Goldsmith was brought up in a council estate in Hounslow, west London, and initially worked as an IT operator before becoming an entrepreneur.

His father was a painter and decorator from west London and his grandfather worked as a miner in Durham.

His fortune was made after he set up an IT recruitment company that he sold for an estimated £17million before buying a a villa in Ibiza, which he called 'La Maison de Bang Bang.'

In 2009, he was recently divorced and living at the villa, where Prince William and Kate had stayed in 2006, with a former lap-dancer called Antonia.

An undercover reporter filmed him boasting about cocaine use and advising how one might meet Brazilian prostitutes.

Goldsmith ploughed the millions he made from selling his villa to by this home in Ibiza

He called the house, which has a Picasso etching in the bathroom, 'La Maison de Bang Bang'

On tape, Goldsmith then comments that when William and his niece got married, he'd gain access to Buckingham Palace.

Speaking in 2013, he said: 'People like to think that I'm this black sheep, a bad boy. I'm not really. I've had my moments – I'm not totally innocent – but am I disliked by my family? No, that is simply not true. I've got a good heart and I care about people. We have never fallen out.'

His sister Carole left school she went on to work for British Airways when he was still a teenager. She met husband Michael at the airline and they later had Kate and Pippa.

He once described the differences between him and his sister, saying: 'I'm the City yuppie and she's the country girl. While I was driving a Lotus Esprit in my Gucci shoes, she had an Alfa and wore Hunter wellies.

'I used to call her the 'original Sloane Ranger' while she called me a 'tearaway' or 'scamp'. I'm a Thatcher child. I'm Captain Ambitious.'