The Prince of Wales has been surprising his staff by popping up hunting for plastic in his households, in a bid to challenge them to follow his green message, royal sources have said.

Charles, a long-time environmental campaigner, is on a personal mission to stamp out single-use plastic in his quarters and make the workplaces more environmentally friendly.

Clarence House, in its annual review, also reported a 57% cut in carbon emissions from the prince’s official travel, mostly due to choosing scheduled flights over chartered aircraft.

Meanwhile, senior aides have been encouraged by the prince to stop taking paper to meetings, and to rely on digital devices instead.

The prince is known for his love of letter writing, but even he turned to an iPad during the coronavirus lockdown.

At the annual review of the prince’s financial accounts, a senior royal source said: “I have to say he recently went through bits of the operation seeing how much plastic he could personally find in order to challenge us all to get rid of it.

“It caused a certain amount of consternation as he popped up in all sorts of slightly unexpected places, literally on a hunt for plastic to see what we could do to remove it from all of our workplaces.”

The source added: “A lot of his communications during lockdown had to go digital – it wasn’t as possible for things to be signed in the way they would have been before.”

They said that those changes would continue to some extent, but Charles remained a devotee of the written note.

“The prince is also a great believer in the power of letter writing and he’s a great supporter of the Royal Mail.

“And so I don’t think we’ll see a complete shift from one to another, but where it is possible to do things online digitally, we are absolutely doing that,” they said.

Carbon emission for the prince and the Duchess of Cornwall’s official travel dropped by well over half, from 2,773 tonnes in the previous year to 1,184.

The source added: “If we can go scheduled, whenever we can go scheduled, we do. Sometimes it just isn’t possible.”

Some 92% of Charles’s office and domestic energy now comes from renewable sources.

Charles and Camilla carried out 580 engagements, visited 90 towns in the UK, and travelled to 48 counties in 2019/2020, and the couple have also been increasing their use of electric cars while travelling to engagements.