Jailed student protester Charlie Gilmour is being locked up for 23 hours a day, according to his mother.
Polly Samson, who is married to Pink Floyd guitarist Dave Gilmour, also claimed her son had been offered pickpocketing lessons by another inmate.
Ms Samson described her son's 16-month sentence for violent disorder during last year's student fees protests as a "disgrace" and a "waste of his time and our tax".
Posting on a Twitter account linked to her official website, the author revealed that Gilmour "seems to be coping remarkably well despite being locked in 23 hours a day".
The 21-year-old was seen hanging from a Union flag on the Cenotaph and leaping on to the bonnet of a Jaguar car which formed part of a royal convoy during the London demonstrations.
Kingston-upon-Thames Crown Court heard that the Cambridge University student had taken LSD and valium in the hours leading up to the violence.
Gilmour admitted violent disorder and was jailed on July 15.
Since then, Ms Samson has been posting tweets saying she is "so proud" of her son.
On July 29 she said she received a letter from Gilmour which revealed he had been offered pickpocketing lessons.
"Pickpocket has offered tutelage but shortage of pockets on prison uniforms," said Ms Samson.
On the same day she described her son's generation as "alienated" and "the ones who will be paying for our dotage".
She also advised protesters to wear balaclavas, in response to another tweeter.
"I would advise anyone who's thinking of protesting to wear," she said.
"Is so unfair that only one side gets to wear armour."
On July 31 Ms Samson said her husband had written to their local MP and urged "everyone" to do so.
Her son turned to drink and drugs after being rejected by his biological father, the writer Heathcote Williams, his lawyer said in court.
Among his achievements were a scholarship to Sussex public school Lancing College, four A grades at A-level, a place to read history at Cambridge and a high 2:1 in his first year university exams.
At the time of his sentencing, the University of Cambridge said it could not comment on whether Gilmour would be able to return to his course on his release from prison.