Sir David Attenborough reveals the one thing that will make him retire

He's still going strong...

Sir David Attenborough has revealed that he will only ever consider retirement if the standard of his work begins to dramatically slip.

The 91-year-old broadcasting icon discussed the prospect of retirement in an interview with the Radio Times, as he prepares for a busy 2018 that will see him gearing up to front a new series of Natural World.

“I would like to think I would be able to detect when I couldn’t find the right words any more,” Attenborough said about the prospect of disappearing from television together.

“If I think I’m not producing commentary with any freshness, or which is apposite or to the point, I hope I would be able to recognise it before someone else told me.”

Attenborough added: “I spend a lot of time fiddling with the words. I write a commentary, and feel it’s finished, then go back over it the next day and find it full of infelicities, clumsiness and redundancies.

“If I thought I was turning in substandard work, that would stop me.”

Meanwhile, Attenborough recently hit out at Bear Grylls for killing animals for television entertainment.

The legendary naturalist has criticised his fellow documentarian for his show ‘The Island With Bear Grylls’, in which he and contestants slaughter animals including pigs, turkeys and crocodiles.

 “We’ve never killed an animal,” Sir David told The Sun. “Bear Grylls will have to answer for himself.

“But I wouldn’t willingly kill an animal just to get a shot.”