Queen Charlotte, wife of the new king, was one of the leading figures of the Gustavian Party, and often visited ex-queen Frederica in her house arrest and worked for prince Gustav to be acknowledged as heir to the throne.

Adlersparre became upset and expressed the opinion of his party that none of the instigators of the coup would accept this as they feared that the boy would take revenge against them when he became King, and that they would go as far as take up the old rumour that the deposed King was, in fact, illegitimate and the son of Queen Sophia Magdalena and Count Adolf Fredrik Munck af Fulkila to prevent this.

[4][page needed] Between the time after the coup and before the royal family left Sweden, they were held under house arrest.

During that period, Queen Charlotte described him in her famous diary as an obedient and dutiful child with a great ability to learn.

He served as an officer to the Habsburgs of Austria, and in 1829, Emperor Francis I created him Prince of Vasa (German: Prinz von Wasa-Holstein-Gottorp).

In 1828, he became engaged to Princess Marianne of the Netherlands, but political pressure forced an end to any wedding plans.