It's remarkable, actually, how it has turned out.

Has it changed that much since you last saw it?

A little bit, yeah.

The King's role certainly changed.

He was Prince of Wales when the artist started.

Someone asked me if I get nervous before unveilings, and I said, well, no, not normally, but then the subject doesn't normally become king halfway through the process.

The monarch butterfly here, a symbol of metamorphosis from prince to king, and a nod to his love of nature.

It is extraordinary how butterflies do come and land on your shoulder, if you're in the garden sometimes.

It's rather marvellous.

The artist had four sittings with the King, and as for all that red...

The idea for the colour came from that very red Welsh Guards tunic.

You know, if that was on its own, it would dominate the picture.

And therefore, I took the liberty of spraying that everywhere, which also, I think, makes the whole aesthetic more interesting.

And it feels a bit more in tune with the kind of, like, 21st century as well.

Jonathan Yeo has also painted Camilla.

And Prince Philip, back in 2008.

The King earlier had honoured the Archbishop of Canterbury for his role in the coronation.

This his first portrait since the ceremony, capturing his emergence into the role.

Laura Bundock, Sky News.