Prince Charles has fostered an image of a public-spirited campaigner, working to raise awareness of a range of social and environmental issues.
What he has been less keen to reveal is the extent to which he abuses his position by seeking to influence government ministers – a direct breach of the constitutional boundaries on which our current system of politics relies.
It could be health, education, the environment or planning – in fact, there are few contentious political issues that Charles hasn't raised personally with government. To make things worse, his eccentric views are regularly at odds with both public and expert opinion.
Charles's letters to ministers (known as "black spider memos") are so outspoken that attorney general Dominic Grieve vetoed their release under freedom of information laws, saying they would be "seriously damaging to his role as future monarch".
And when Charles wants to keep his lobbying at arm's length, he has a range of pressure groups whose staff enjoy privileged access to Whitehall and even has senior aides seconded to government departments.
All of which means Charles has lost any claim to be an impartial figurehead - he's a political prince who wants to be an activist king.