A car dealer smashed his Mercedes into a family's people carrier and threatened to slap a mother-of-three a court has heard.

Company director Christopher Dickson, director of Dicksons of Perth, left his victim's three young children screaming after writing off their car and then violently confronting their parents during the road rage incident, the Daily Express reports. 

He left the scene and later drank a glass of wine in front of police officers when they arrived at his home to breathalyse him. 

Caravan and used car dealer Dickson - who told his victims he had been drinking all day - was found guilty of a series of charges yesterday at Perth Sheriff Court.

The 29-year-old was banned from driving on an interim basis by Sheriff Gillian Wade, who deferred sentencing for reports.

Witnesses Alexander and Julia Nicoll said Dickson had driven his £40,000 Mercedes aggressively in Perth prior to the incident that wrote off their Ford Galaxy.

They told the court Dickson cut in front of them before slamming on his brakes, causing them to run into the back of his C-class estate. 

They said that Dickson got out of his car and was banging their windows and swearing as their three children cowered in the back seats.

Mrs Nicoll said Dickson smelled of alcohol and bragged that he had been on a day-long binge drinking session before telling her he would give her a slap.

Constable Martin Buchan said they had traced him at home but as Dickson said he had had alcohol, police had to wait 20 minutes to perform an accurate breath test.

The officer told the court: "He said that since he arrived home he had consumed a quantity of alcohol. He had had two tins of lager and a glass or so of wine." 

Dickson, of Croft Park, Perth, admitted during evidence he told Mrs Nicoll he'd slap her but claimed he was entitled to because there was a confrontation with the couple. 

Sheriff Wade found him guilty of drink-driving in Perth in February last year.

He was also found guilty of careless driving by causing a crash, and behaving in a threatening manner by shouting, swearing and uttering threats of violence. 

The sheriff noted Dickson - who had been at his brother's funeral two days before the incident - had a previous drink-driving conviction from 2008, and deferred sentencing.