Prince Charles is a man of strong opinions on some subjects: architecture, rural affairs, homeopathy. Like anyone, he is entitled to his views. But like anyone who has special access to the corridors of power, he can expect his role to come under scrutiny.

The Observer today reveals a row over whether he has undue influence on health policy, particularly when it comes to alternative therapies. Charles has extolled the virtues of herbal remedies and acupuncture and lobbied for them to be more widely available on the NHS. With limited resources for all medicines, that is a controversial view.

The public has an interest in correspondence between Clarence House and the Medicines and Healthcare Products Regulatory Agency. This, the main drugs authority, gave purveyors of homeopathic remedies new freedoms to claim medicinal benefits when selling their products. But this correspondence cannot be requested under the Freedom of Information Act because of a special clause (section 37) which exempts royal households on the grounds that they are not public authorities.

That may be true for some royals, but Charles takes full advantage of his privileged position: he summons officials for secret meetings; his letters are fast-tracked to ministerial red boxes.

The Queen has protected the legitimacy of her reign by staying removed from politics. On succession, Charles would be well-advised to do the same. Meanwhile, if Clarence House wants to champion causes, it must be more open and transparent about it. Prince Charles must bear in mind that, while meddling by an heir might be deemed improper, the same behaviour by a king could trigger a crisis.