Sir David Attenborough has revealed he chose to have a pacemaker fitted so that he could be insured to go on long haul flights.

The TV naturalist, 87, told the Radio Times that having the operation in June was "no big deal" and it enabled him to continue travelling the world.

David, who is presenting a two-part documentary on the ascent of man, Rise of Animals, on BBC2, explained why he had had the operation.

"When you're in your 80s, your heart gives you a funny five minutes every now and again and they won't insure you unless you have a cardiologist to say that you can go on a long-haul flight. So I had to have the pacemaker," he said.

The wildlife star, who previously had a knee replaced, said of the possibility of retiring: "I don't think so. If you've got a motorcar and its brakes fail, and you have the capacity to replace them, you replace them. And we have the capacity to replace knees, which is wonderful.

"I don't ever want to stop work. Sure, something's going to wear out some time and I won't be able to do it, but while I can - and people want me to, and people look at the result - I'm delighted to work. If I was earning my money by hewing coal I would be very glad indeed to stop. But I'm not; I'm swanning around the world looking at the most fabulously interesting things. Such good fortune."