Prince Charles campaigned for more grammar schools during the time of Tony Blair's government, the former education secretary has said.
"He was very keen that we should go back to a different era where youngsters had what he would have seen as the opportunity to escape from their background, whereas I wanted to change their background," David Blunkett said.
The Prince of Wales didn't like" it when his request was refused, according to a BBC Radio 4 documentary.
"I would explain that our policy was not to expand grammar schools, and he didn't like that."
Mr Blunkett is one of three former cabinet ministers interviewed for the documentary, The Royal Activist, the BBC reported.
Mr Blunkett added: "I can see constitutionally that there's an argument that the heir to the throne should not get involved in controversy; the honest truth is I didn't mind."
More top news
TV presenter Helen Skelton is a supporter of the campaign and is calling for more parents to get out on their bikes with their children.
Mrs Justice Nicola Davies will sentence Berlinah Wallace, 48, at Bristol Crown Court.
The JR4NHS group was founded by three doctors and a university professor, and supported by the renowned physicist until his death in March.