A source from the "The King's Foundation" said the monarch's charity was "looking forward to working with Amazon on a one-off documentary to showcase His Majesty's philosophy of Harmony, and the work it has in turn inspired around the world to build sustainable communities and transform lives.

"We are looking forward to sharing our mission and promote the benefits of Harmony more widely as we embark on this landmark film," the source told PA.

The Amazon partnership bucks tradition for the Royal Family, which usually teams up with big UK broadcasters for on-screen appearances.

According to the website of the king's foundation, the Philosophy of Harmony posits "that by understanding the balance, order and relationships between ourselves and the natural world, we can create a more sustainable future."