• Read Sir David's response

Nine-year-old Tristan Dillon doesn't get much mail, so it was a big day when a letter arrived at his Thirroul home.

Excitingly, it came in an air mail envelope that was simply addressed, in unfamiliar handwriting, to "Tristan".

"Dear Tristan," the letter began.

"Thank you for sending me such a spectacular drawing of a striking snake. I think it is excellent. I am so glad you enjoy my programmes. With best wishes, David Attenborough."

Tristan, a reptile enthusiast who estimates he has seen at least 20 documentaries by British national treasure Sir David, had earlier written to his idol in admiration, enclosing a detailed drawing of a snake with his letter.

He told the Mercury he was always hopeful the kindly naturalist would reply.

"He's a great man and he knows a lot about nature," said Tristan.

"I just appreciate his movies and documentaries."

Tristan's father, Steve Dillon, was more surprised by Sir David's "beautiful, personal gesture".

"He has so many people he knows around the world, and he took the time to write a personal letter. I think that just reflects his nurturing of the younger generation's interest in natural history."

Sir David, 87, confirmed his allegiance to traditional modes of communication during a recent interview with UK tabloid The Sun, in which he expressed frustration with impersonators who set up Facebook and Twitter profiles in his name.

He branded the accounts "horrible" and "rude" and said his lawyer had acted to have them taken down. He assured fans he didn't use social media.

"God knows why [others use it]. I don't," he said.