Prince Charles says he'll stay quiet about controversial topics when he's King

Britain's Prince Charles has pledged not to interfere in the affairs of state when he becomes king, seeking to dispel concerns about his past activism on issues ranging from global warming to architectural preservation.

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In the past he’s spoken out about the environment, among other things, but he’ll stick to constitutional conventions when he’s the King. Source: Breakfast

In an interview for a documentary marking his 70th birthday, the heir to the throne told the BBC that he understands he will have to act differently when he becomes king.

Britain's monarch is barred from interfering in politics.

The prince has caused disquiet in the past by expressing his commitment to organic farming, traditional architecture and environmental causes.

In 2015, he lost a long court battle to prevent the disclosure of 27 letters sent to government officials on matters such as badger culling, fish protection, military readiness and the preservation of historic buildings.

The "black spider" memos, so called because of Charles' cramped handwritten greetings and closings, were controversial because some saw them as inappropriate lobbying by the heir to the throne.

But Charles defended his past actions, including establishing the Prince's Trust in 1976 to help disadvantaged young people, saying he had always steered clear of party politics.