Tom Berkeley said they had planned for months to sing Happy Birthday to James Martin at the Oscars if they won for Best Short Film.
Both came to pass on Sunday night at the Dolby Theatre as An Irish Goodbye was announced as the winner of the category. On stage, after a brief few words to thank those who had helped them make the film, Berkeley teed up the audience to serenade Martin, one of the stars of the film.
An Irish Goodbye - which you can watch on the RTÉ Player - sees two estranged brothers reunited on the family farm to complete their mother's bucket list following her death.
Northern Ireland film An Irish Goodbye has won an Oscar for best live action short film.
— BBC Breakfast (@BBCBreakfast) March 13, 2023
Martin, an actor with Down syndrome who turned 31 on Sunday, plays Lorcan, while Seamus O'Hara plays Tulourgh.
"When we found out many months ago that the Oscars would fall on James's birthday, we'd always say that if by any chance we were going to end up on that stage, we'd all band together and sing the man through. It's something we'd wanted to do for a long-time," said Berkeley, who wrote and directed the film along with Ross White, told BBC.
"This is completely overwhelming," said White.
"We're just so proud to be representing Northern Ireland, where we come from. This film has been such a joy, and such a big part of our lives for a number of years. To be on that stage in front of all our cinematic heroes, to be sharing this moment, and singing Happy Birthday to this man..."
Martin, a Belfast native, said it was "nice" to have everyone sing to him.
"Not just Harrison Ford, everyone else... Colin Farrell, Brendan Gleeson, Brendan Fraser... I could name a lot," he said.
Speaking to Virgin Media's Zara King after the ceremony, Martin thanked the charity Mencap - which supports 42,000 people with a learning disability and their families in Northern Ireland - for their help.
"I'm the first person with Down syndrome going over to America to pick up these Oscars," he added, before leading a rendition of I'll Tell Me Ma.
James's father Ivan told BBC Radio Ulster on Monday morning that there "were a few tears shed" following his son's win.
"Ultimately, the person who said to me, 'Look, Mr Martin, you're going to have to realise that James will probably never speak' - he had the bedside manner of Atilla The Hun," said Ivan.
"Here we are, and James not only speaks, once he started speaking, he hasn't shut up since. He loves the acting. He loves this ride, the Oscars and the Baftas.
"You get to the Oscars, and everybody keeps saying that the prize is getting there but truth to tell, you want to win.
"He's taken it head on, he's done very well. We're delighted for him. He tackles everything with great gusto. It's certainly paid off this time.
"Last week, he was with [James Bond film producer] Barbara Broccoli. They were chatting, and this guy comes over, and Barbara introduces him to [James]. The guy says, 'Ah yes, James, schmoozing up to Barbara Broccoli because you want to be the next Bond.
"James looked at him, and said, 'Don't be so stupid! Look at me, look at what height I am - I'm too small to be James Bond'. He turned around to Barbara and said, 'But I've got all the moves'."
In all the excitement and glory James and the @AnIrishGoodbye_ team still had time to give a shout out to Mencap!!
Now for the homecoming 🙏💕 https://t.co/SNd1j6dmYM
— Mencap NI (@Mencap_NI) March 13, 2023