They’re both considered to be national treasures, they’re both 91 and they’re both fighting climate change in 2018, one tree at a time.

Due to air on Monday 16 April, The Queen’s Green Planet, featuring both Sir David Attenborough and the Queen, sees the duo stroll around Buckingham Palace’s gardens with the Queen cracking more than a few jokes.

At one point during the filming, a helicopter flies overhead, and the Queen asks: “Why do they always go round and round when you want to talk?”

And then she jokes: “Sounds like Donald Trump”.

Attenborough also suggests that climate change might lead to “all kinds of different trees growing here [the UK] in another 50 years.”

The Queen replies: “It might easily be, yes. I won’t be here though.”

As the pair continue chatting and strolling beside the grass, Attenborough admires the Queen’s sundial but also points out that (uselessly) it’s been positioned in the shade.

“Had we thought of that? That it was planted in the shade, it wasn’t in the shade originally, I’m sure?,” she says, smiling.

She adds: “Maybe we could move it?”

The documentary, based on a project called The Queen’s Commonwealth Canopy, a plan to create a network of forest conservation projects dedicated to the Queen in all 53 countries of the Commonwealth, explores the Queen’s passion for nature.

The Queen and David Attenborough joke about Donald Trump in new documentary