The tearaway son of Stagecoach tycoon Brian Souter chased a stranger and rained blows down on his head after the victim verbally abused his father at a drunken party.
Scott Souter rounded up a group friends to pursue Philip Johnston as he drove away from the party before pulling him over on a quiet road and attacking him.
On Wednesday, Perth Sheriff Court was told that the multi-millionaire and his wife had since ordered his teenage tearaway son to go to anger management and alcohol counselling sessions.
Souter, who admitted leaving his victim battered and bruised, was fined £200 and ordered to pay £400 compensation to Mr Johnston.
Fiscal depute John Malpass said: "The accused was not known to the victim. During the evening the complainer and several friends attended a party in Glenfarg. The accused and others were also in attendance.
"During the evening, as alcohol had been consumed, there appeared to be some tension between them. As a result the complainer and his friends decided to make their way home and left the party.
"They drove along the A912 towards Bridge of Earn. They became aware of a vehicle approaching from the rear, flashing its headlights. Mr Johnston slowed down to allow it to pass, which it did."
Souter and his friends pulled in ahead of Mr Johnston's car forcing him to stop and then they got out and staged an angry confrontation in the Perthshire countryside.
Mr Malpass said: "The accused and others from his vehicle exited and approached. There was some shouting and the accused punched Mr Johnston several times to the face and head through the open window."
He added: "The accused was interviewed and admitted he was at a party when persons at the party began to make fun of his family and his father."
Souter, 18, who gave his father's address in Glasgow Road, Perth, pled guilty by letter to a charge of assaulting and injuring Mr Johnston by punching him repeatedly to the face and head on the A912 Glenfarg to Bridge of Earn road in Perthshire during the early hours of August 8 this year.
Paul McBride QC, defending, said his client had already stumped up around £400 to pay for damage to 20-year-old Mr Johnston's car.
He said: "He and members of his family were subjected to abuse and obscenities and he took matters too far. He accepts full responsibility for the offence. He appears genuine in his remorse. Since then he has taken significant steps to reduce any possibility of reoffending, both at his own instance, and urged by his family.
"He has already had the embarrassment of suffering the conviction and can assure you that steps taken by his family - who have spoken to him in the strongest possible terms - will ensure no incident of this type will take place in future."
Sheriff Michael Fletcher said he noted that Souter had not simply acted in the spur of the moment, but had actively chased his victim for some distance before stopping him to launch the attack.
In 2007 the tearaway teenager took his father's powerful sports car and drove it the wrong way down a one way street while he was uninsured. He was just 15 when he admitted the offence at Perth Sheriff Court and was banned from driving for 18 months. In June this year he got an on-the-spot fine for being drunk in public in Stirling.
