Their friendship was cemented in 2015, when they met in Washington for an informal chat at the White House to promote the Invictus Games in Florida.The following year, the Obamas had dinner at Kensington Palace and met Prince George, then two, who was brought down in his pyjamas and dressing gown.The young prince immediately charmed them by playing on a rocking horse they had given him for his first birthday and a cuddly toy dog they had sent him as a gift when Princess Charlotte was born. Prince Harry and Barack Obama discuss the format of the interview Credit:BBC Prince George meets Barack ObamaCredit:Kensington Palace/Pete Souza Barack Obama and Prince Harry watch the wheelchair basketball at the Invictus GamesCredit:Samir Hussein Michelle Obama has called him “Prince Charming” and more recently, “my friend,” when he joined her in October for a surprise visit to local schoolchildren in Chicago.While Prince Harry has never publicly voiced an opinion on Donald Trump, Mr Obama’s successor, Ms Markle has been less restrained – calling him “misogynistic” while he was campaigning and even threatened to move out of the United States if he was elected.The BBC confirmed that Sarah Montague will be one of the two presenters who will host Prince Harry’s edition of Today from the BBC studio.It will mark her return to the BBC after a period of absence which is reportedly due to a battle with BBC bosses over the sizable pay gap between her and her male colleagues.The last royal to guest edit the Today show was Sarah, Duchess of York, in 2004. The interview took place in Toronto in September, when the Prince was in Canada for the Invictus Games.The conversation covered topics including Mr Obama’s memories of the day he left office and his hopes for his post-presidential life, including his plans to focus on cultivating the next generation of leadership through the Obama Foundation. The pair are firm friends and have fostered a so-called “bromance” with numerous public appearances together over the years.But when a slightly awkward Prince Harry came to interview Barack Obama for his stint as a guest editor on BBC Radio 4’s Today programme, he admitted he was nervous, prompting the former US President to reassure him it was all a bit of fun.As the pair came face to face on camera, sitting across a table from each other behind the radio microphones, Mr Obama jokingly asked the Prince if he should speak with a British accent.He also wondered if he should speak faster than usual because he was a “slow speaker.”But the Prince replied: “No, no not at all. But if you start using long pauses between the answers you’re probably going to get the face.”When Mr Obama asked to see “the face” Prince Harry gave him a stern look, prompting the US politician to laugh; “I don’t want to see that face.” As Prince Harry began explaining how part of the interview would be packaged for his guest stint on the Today programme, to be broadcast on December 27, while the whole interview would be released as a podcast, a more relaxed Mr Obama appeared keen to crack on.“It’s going to be fine,” he said.“Excellent. I’m ready whenever.”Prince Harry noted: “You’re excited about this, I’m nervous about this that’s what’s quite funny.”Mr Obama reassured him it was all “fun” but offered to turn the tables and interview him instead, to which the Prince quickly replied: “No no, let’s keep it this way, I’d much prefer that.”The Obamas have been touted as likely invitees to Prince Harry’s forthcoming wedding to Meghan Markle. At the Invictus Games, Mr Obama was overheard asking Prince Harry about his relationship with Ms Markle as they watched the wheelchair basketball and was one of the first to congratulate them, on Twitter, when the engagement was announced. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.