The Queen's Green Planet, ITV

It all came down to our final shoot, one summer’s day in June last year: a simple walk through a garden with two 91-year-olds.

The gardens were those of Buckingham Palace, and our contributors two of the most prestigious pensioners on the planet, but the idea was simple: a conversation between two old friends.

They had plenty to talk about. The Queen can trace her ancestry through the trees of Buckingham Palace garden, from the London planes planted by her great, great grandparents, to oak trees planted for her own children.

Her companion on the day, the inimitable Sir David Attenborough, remains endlessly fascinated by the natural world, and, crucially, he is almost uniquely comfort able in Her Majesty’s company.

In some ways, it was the simplest shoot in a challenging 18 months of on/ off production that had taken our small team from the lush, verdant rainforests of the Caribbean alongside Prince Harry to the unique wilderness of the Great Bear Rainforest in Canada with the Duke and Duchess of Cambridge.

We were following the progress of the Queen’s Commonwealth Canopy, an extraordinary environmental initiative designed to protect the bountiful forests of the Commonwealth both now and for future generations.

A simple shoot then, but not without its challenges. There would be no rehearsal, and no second takes. Timing was tight, and every step required careful planning.

In the hours before the walk, we recced the route one final time, then ate our sandwiches in the cool shade provided by the great London plane trees that dominate the palace garden.

In the end, it was a day of perfect timing. The sun was out and the roses in bloom, but most crucially, the comic timing of our two remarkably playful contributors made the most welcome surprise. The pair sparked off each other, making jokes and sharing stories as they wandered among the trees.

This was a rare treat to witness – and an even rarer one to capture on film.

As the conversation flowed, the subject matter became more intimate. The Queen spoke profoundly of her legacy, of a time when the trees in the garden will change, though she will not be around to see them. It was a fitting conclusion to a production full of quite extraordinary moments.

Cut to south-west Africa, earlier that same month. As I sat in the back of a tiny turbo prop plane piloted by Angelina Jolie, flying low over the Namibian desert as the sun set among the dunes, all I could think about was whether I’d pressed record on the GoPro suckered to the cockpit.

There was enough room – just – for two in the back of the aircraft, but with the main camera on a fixed 50mm prime, we needed that wide shot looking back towards the film icon actually flying the plane. As we prepared to take off, I had a chat with Angelina about her sunglasses.

As you would imagine, the bright African sun meant she was wearing shades (effortlessly cool A-list aviators, naturally), but this was a key scene where she would talk personally about her love of Namibia, and about the conservation work that needs to be done here.

It would be nice to see her eyes. On the other hand, she was flying the plane, and it would be nice if she could see.

As it turned out, she was an excellent pilot, but she is a film-maker too, and was keen to get the right shot. So off came the glasses and off we flew into the African sunset to shoot a beautiful sequence in the skies above the desert.

Keeping it simple

These were not overly expensive shoots. When you have David Attenborough and the Queen together for a short sequence, the tendency might be to pile on cameras and crew, to cover all angles and maximise coverage.

The Buckingham Palace garden scene was shot on a single camera, with very little time for cutaways or non-synch footage, but the result was considered and magical: an intimate feel, both on the shoot and on screen, with a distinctive and consistent visual tone.

Likewise in Namibia, which was also shot towards the end of our production process (and budget), a skeleton crew – equipped with an Arri Amira and a GoPro – kept logistics simple, the atmosphere relaxed and intimate, and focused on what mattered: passionate contributors talking about an extraordinary project. That might just change the world.