The presence of a political king in Buckingham Palace is more likely than not to be troublesome for the prime minister of the day.
Just ask Boris Johnson – who endured a bitter clash with Charles over the Rwanda deportation scheme when the monarch was still prince of Wales.
But when it comes to the now-King’s vocal support for the green agenda and tackling climate change, Rishi Sunak may be counting his blessings.
The Prime Minister’s environmental record has come under heavy attack in recent days following the resignation of Lord Goldsmith as a climate minister, with a claim that Mr Sunak is “simply uninterested” in the green agenda and had “shredded” the UK’s global reputation on the issue.
It could have proven embarrassing as Joe Biden, who has passed landmark climate legislation at home in the US, visited for talks on Monday.
The pair did discuss strengthening clean energy supply chains, but in the context of boosting energy security amid Russian aggression rather than the battle against climate change.
So it is good for the UK that after leaving No 10, Mr Biden then went to meet Charles, where the King is almost certain to have spent a large chunk of the conversation lobbying for action after the hottest June on record.
Unlike Mr Sunak, the King is the real deal when it comes to environmental issues, having championed the green agenda for years and long before it was fashionable.
Some would say he should not be getting into politics, but given the scientific consensus around climate change and the need to save the planet from catastrophic global warming, he could well argue that it is no longer a political agenda.
As a poll for i found in May, 38 per cent of Britons think the monarch should be speaking out on the issues that concern him, a figure that rises to 45 per cent among 18 to 24-year olds.
It is also useful for Mr Sunak that the UK can still boast that it has one of the world’s leading voices on the agenda, and will help burnish that international reputation, even if the Government is perhaps not.