The mother and son shovelled soil around the copper beech sapling to mark the Queen’s Platinum Jubilee next year.
The planting is part of the Queen’s Green Canopy scheme to mark her historic 70 years on the throne – a feat achieved by no other British royal.
Charles, who is the nation’s longest-serving heir apparent, has often been reported to favour a “slimmed down monarchy”.
However, according to Richard Fitzwilliams, the future King’s alleged plan to cut down the number of core royals is ill-defined.
Prince Charles’ plan for ‘slimmed down monarchy’ dismantled: ‘Not clear what that means’
Prince Charles: Plants tree with Queen at Balmoral
The royal commentator and film critic told Express.co.uk that the exact meaning of Charles’ reported plan remains unclear.
He said: “There are talks of the so-called slimmed down monarchy but it’s not clear what that means exactly.
“This is a phrase that we have to decide what that means, it hasn’t been defined.
“The point with the so-called slimmed-down monarchy, it very much came into being – in the inner core so as to speak – at the end of that balcony appearance at the end of that Diamond Jubilee celebrations.
“That of course was when [Prince] Harry was still single and of course the Duke of Edinburgh – though he wasn’t there because he was hospitalised – was alive.
Premiere: Charles With Camilla, William and Kate
“What I think we will be seeing is some form eventually obviously, some form of clarification of what this may mean.”
The royal expert added that Charles “couldn’t possibly be an activist king” when he accedes to the throne.
The Prince of Wales has often faced allegations that he is acting politically by championing various causes.
Over the years he has campaigned on several issues, including climate change, architecture and GM crops.
In the 2018 BBC documentary, ‘Prince, Son and Heir: Charles at 70’, he sought to dispel worries that he may be an “activist king”.
Charles: Said to favour a slimmed down monarchy
Charles said: “You can’t be the same as the sovereign if you’re the Prince of Wales or the heir.
“But the idea somehow that I’m going to go on in exactly the same way if I have to succeed, is complete nonsense because the two situations are completely different.
“You only have to look at Shakespeare plays, Henry V or Henry IV part I and 2, to see the change that can take place.
“Because if you become the sovereign then you play the role in the way that it is expected.
“So, clearly I won’t be able to do the same things I’ve done as heir.
“But it’s a different function. I think people have forgotten that the two are very different.”
Mr Fitzwilliams claimed that neither Prince Charles nor Prince William be engaged in activism when they become King.
He said: “I think there is absolutely no question that he certainly was never inclined to – as Charles was not, it’s not in the job – any form of activism.”
Source: EXPRESS CO UK