Charlie Gilmour, son of Pink Floyd guitarist David Gilmour, has been jailed for 16 months for a rampage at a student fees protest in central London.
Gilmour, 21, was accused of throwing a bin at a convoy of cars containing Prince Charles, sitting on a protection officer's car and smashing a window.
The Cambridge University student, of Billingshurst, West Sussex, was bailed in May so he could finish his exams.
Kingston Crown Court heard he had taken LSD and valium before the incident.
Gilmour was among thousands of people who protested in Trafalgar Square and Parliament Square on 9 December 2010.
He was photographed hanging from a union flag on the Cenotaph during the march, an incident for which he later apologised.
He was also seen leaping on to the bonnet of a Jaguar car that formed part of a royal convoy containing the Prince of Wales and Duchess of Cornwall and hurling a rubbish bin at the vehicle.
The car carried royal protection officers accompanying the couple as they were chauffeured up Regent Street in a Rolls-Royce to a Royal Variety Performance.
Gilmour's barrister David Spens QC argued he was "ashamed of himself" for his behaviour, which was sparked by his "intoxication by drink and drugs", and had no recollection of throwing the bin.
He was described as "out of his mind" by the time he arrived in Parliament Square that day as he had been drinking and taking drugs since the previous night.
This was the culmination of a continual binge that had started around August, "born out of unhappiness rather than hedonism".
Mr Spens told the court this had been precipitated by an "emotionally painful" meeting that summer with his biological father writer Heathcote Williams.
Gilmour also kicked at the window of Topshop's flagship store on Oxford Street and ended up in possession of the leg of a mannequin.
He was filmed shouting: "They broke the moral law, we're going to break all the laws."
Passing sentence, Judge Nicholas Price QC accepted that Gilmour's behaviour at the Cenotaph did not form part of the violent disorder, but accused him of disrespect to the war dead.
"Such outrageous and deeply offensive behaviour gives a clear indication of how out of control you were that day," he told Gilmour.
"It caused public outrage and understandably so."
His conduct at the war memorial had prompted a deluge of "vituperative and in many cases obscene emails", he said.
These were "not just to you but, it is with deep regret, to your whole family, who were of course totally blameless", he added.
Gilmour entered a non-specific guilty plea during a hearing in May.
He claimed he had not realised the significance of the memorial - an excuse the judge rejected.
"For a young man of your intelligence and education and background to profess to not know what the Cenotaph represents defies belief," he said.
"You have shown disrespect to those who gave the ultimate sacrifice, to those who fell defending this country."
But Gilmour was given some credit for apologising for his actions.
"You expressed yourself in a fitting way when you said how deeply ashamed you are for what is, as you acknowledge, the terrible insult to those who gave their lives," the judge said.