So just tell me how you began to get into all of this.

The really lovely thing about trees is they get into your family and you never lose them.

So my grandparents had a tree nursery and my great-grandfather used to auction off the chestnut coppice underwood from the Cowdrey estate very near here.

And every year they would have this big sale, they'd cut down all the chestnuts and they would sell it off for fencing and the furniture maker would come and the fence man would come and the...

So I suppose I grew up with trees, but then there's always that moment when you need to have trees removed in order to appreciate them.

And so I think, interestingly, I really became truly obsessed by trees when I was working in Iraq and I was working in the desert.

And there were deep palm groves, but very few trees at various points.

What's happening here in the world now with these constant assaults of new diseases coming more rapidly than ever before?