Charlie Gilmour, son of Pink Floyd guitarist David Gilmour, has been jailed for 16 months for a drink and drugs-fuelled rampage during protests against student tuition fees.
The Cambridge University student admitted violent disorder after he was seen hanging from a Union flag on the Cenotaph and leaping on to the bonnet of a Jaguar car that formed part of a royal convoy.
Gilmour, 21, was also found to have thrown a rubbish bin at the vehicle.
Kingston Crown Court heard he had turned to drink and drugs after being rejected by his biological father, the writer Heathcote Williams, and had taken LSD and valium in the hours leading up to the violence.
Judge Nicholas Price QC said Gilmour's behaviour at the Cenotaph was "deeply offensive" and that his actions had caused public outrage.
He added that to "ignore what you did would be wrong, but to sentence you on it would be improper".
"What you did went far, far beyond proper protest."
Gilmour, from Billingshurst, West Sussex, also kicked at the window of Topshop's flagship store on Oxford Street and ended up in possession of the leg of a mannequin during the riot on December 9.
Minutes earlier he had joined a mob attacking a procession of three royal cars, one containing the Prince of Wales and Duchess of Cornwall, as it made its way up Regent Street.
The Jaguar carried royal protection officers accompanying Charles and Camilla as they were chauffeured to a Royal Variety Performance in a Rolls-Royce.
During one incident he was caught shouting: "Let them eat cake, they said, we won't eat cake.
"We will eat fire, ice and destruction, because we are angry, very f****** angry.
In another clip he is heard to say: "They broke the moral law, we are going to break all the laws. Arson. Destroy.
"We are not going to stand for it any f****** more, storm Parliament."
Judge Price said: "It would, in my view, be wrong for me to ignore who the occupants of the three cars were and that's undoubtedly an aggravating feature."
He acknowledged that Gilmour had a right to protest about student fees and that his "feelings were sincere".
But he warned that this right was not "unfettered" and carried with it responsibility.
Gilmour issued a public apology the next day after he was captured in photographs that showed him hanging from a flag on the Cenotaph.
He said it was a "moment of idiocy".
After he was identified he expressed his "deepest apologies for the terrible insult to the thousands of people who died bravely for our country".
In a statement at the time he said: "I feel nothing but shame. My intention was not to attack or defile the Cenotaph.
"Running along with a crowd of people who had just been violently repelled by the police, I got caught up in the spirit of the moment.
"I feel additionally mortified that my moment of idiocy has distracted so much from the message (the) protest was trying to send out."