Interfering

It is not just his lifestyle that attracts umbrage

His campaigning for causes such as the environment and climate change has led to accusations he is interfering in matters that British royals should avoid.

However, Charles has said it would be "criminally negligent" not to use his position to help people and his role has allowed him to express strong views. That would be impossible for a monarch, who under Britain's unwritten constitution, must remain apolitical.

"There's a whole of lot of things I have tried to focus on over all these years that I felt needed attention, not everybody else did, but maybe now some years later they're beginning to realise that what I was trying to say was not quite as dotty as they thought," Charles said in an interview with younger son Harry in 2017.

His supporters say his causes - such as helping disadvantaged young people find work, and inter-faith dialogue - are often prescient and show concern for his fellow countrymen.

He acknowledges he has challenged orthodox views. He has long railed against a throwaway economic model that has polluted the world's oceans with plastic, now a mainstream concern.

But other views, such as his support for complementary medicine, still attract scorn.

In 2013, it was revealed he had held 36 meetings with government ministers over three years, while two years later, Britain's top court ruled that dozens of his letters to ministers - dubbed the 'black spider memos' because of his scrawled handwriting - could be released.

Topics included rural housing, food in hospitals and the fate of the Patagonian Toothfish.