Challenged by the taxi driver on his access to violence against his fourth wife, he would then be shown aggressive towards her.
"She was asking about what Jacob liked and he said he liked aeroplanes and was asking if he'd seen a Spitfire and we said we liked going to the Science Museum and RAF museum".
When the taxi driver confronted Gary, he became irate, and Julie-Ann told the driver to call the cops.
When at the police station Goldsmith said he had pushed his wife hard but denied hitting her.
Mrs. Goldsmith doesn't remember how it happened, but Gary punched her in the face which knocked her straight to the floor including her head which bounced on the ground.
Mr Goldsmith is the younger brother of Carole Middleton and attended the weddings of both her daughters - the Duchess of Cambridge and Pippa Middleton.
Prince William's wife also appeared to have a brand new hair do, which was much lighter and shorter than it was following her appearance on Remembrance Sunday.
Mrs Goldsmith was knocked to the ground, where she remained with her eyes closed for around 15 seconds before waking up and staggering to her feet, the court heard.
The couple had been at a charity auction at Home House in Portman Square, Marylebone before they clashed.
The court heard the couple began to argue while in a taxi after a charity event, then continued the argument on the street outside their home.
Goldsmith will be sentenced at the same court next Tuesday.
Chief Magistrate Emma Arbuthnot said: "There was a request from the defence that came in to the court for a two week adjournment so that a caution could be looked at".
"But I am really looking at how to protect this lady from this man", she added.
When that marriage broke down he married again six years later to Luan.
She left him amid a reported row over his drug use and he later met and married Julie-Ann.
He was brought up with his sister in Southall, west London.
In 2005, he sold his shares in Computer Futures for £17million and bought a villa in Ibiza and called it "La Maison de Bang Bang". She met husband Michael at the airline and they later had Kate and Pippa.