Sir David Attenborough has discussed the challenges of making nature documentaries at 90, confessing that he is "running into problems" when it comes to his memory.

The naturalist has no plans to slow down with his broadcasting and is currently working on new epic BBC series Blue Planet II, though he is "coming to terms" with the fact he is not as sharp as he used to be.

Speaking to the Telegraph shortly after a trip to the Jura Mountains in Switzerland, he said: "There were these searing yellow fields and I can’t think of the damn name.

"I wanted to say something about it but I couldn’t and it wasn’t until we got quite close to Geneva that I thought, of course, oil seed rape."

Last year, Attenborough told us he shudders at the word 'retirement'.