Sir David Attenborough has said he has been "completely overwhelmed" by the messages he has received ahead of his 100th birthday.
The veteran broadcaster and environmentalist celebrates the milestone on Friday, with a special concert planned in the evening at the Royal Albert Hall in London.
In an audio message released on Thursday, Sir David said: "I had rather thought that I would celebrate my 100th birthday quietly, but it seems that many of you have had other ideas.
"I have been completely overwhelmed by birthday greetings, from pre-school groups to care home residents, and countless individuals and families of all ages."
He added: "I simply can't reply to each of you separately, but I'd like to thank you all most sincerely for your kind messages, and wish those of you who have planned your own local events: Have a very happy day."
