A one-off meeting between Barack Obama and Sir David Attenborough will be repeated on BBC1 this month after its first screening attracted 2.5 million viewers.
The encounter between the US president and the broadcasting veteran was given an off-peak slot at 10.30pm last Sunday despite its star billing.
The half-hour programme still managed to attract a huge audience, beating the 798,000 who tuned in to watch the Who and Chemical Brothers perform live at Glastonbury on BBC2 at the same time.
It was also one of the most popular shows on BBC iPlayer after viewers complained they missed the late night live transmission and were forced to catch up online.
Writing on Twitter, one fan, Emma Richmond, said: “President Obama interviewing David Attenborough? That’s just too cool!! Why on so late at night BBC? Should be on primetime.”
Another, Jonathan Ogilvie, added: “Seems odd the Beeb put the Obama Attenborough interview at 10.30pm on a Sunday night (and opposite the Who!).”
BBC sources said the fact the special programme was only half an hour long meant it was impossible to fit earlier in the schedule.
It will be repeated at 6pm on Sunday, July 12 on BBC1.
The meeting at the White House was recorded in May on Attenborough’s 89th birthday. He was interviewed by Obama about climate change, overpopulation and his views on what can be done to protect the natural world.
The president said he was a “huge admirer” of the naturalist’s work, having watched his films since he was a child.
He added: “We’re not moving as fast as we need to and part of what I know from watching your programmes, and all the great work you’ve done, is that these ecosystems are all interconnected.
“If just one country is doing the right thing but other countries are not then we’re not going to solve the problem, we’re going to have to have a global solution to this.
“What we’re seeing are global trends that depend on the entire world working together, and sadly we haven’t made as much progress as we need to on climate change.”
Attenborough said: “On my 89th birthday it was to my considerable surprise to find myself in a place that I’ve never been to before to visit the White House with the president of the United States. He was friendly, hospitable and genuine.”
The programme has also been shown on BBC America and on ABC in Australia, and will be screened in more than 50 countries.