Brian Byrne, from Navan, Co Westmeath, was chosen by the Late Late producer Michael Kealy to compose the signature tune with Ryan Tubridy's love of jazz in mind.
And Los-Angeles based Byrne is now hitting the high notes in Tinseltown, as he is working on an arrangement for the much-anticipated Sex and the City sequel. He revealed: "I'm arranging a song and I'm working with the orchestra for it, and playing piano on it. A high profile figure, who will be in the film, is going to sing the song."
Byrne is remaining tight lipped who the star actress will be, and is focusing his mind on going into record the song tomorrow in LA.
At the beginning of Tubridy's Late Late Show debut on September 4, the star thanked Byrne for his work on the piece.
"He heard the drums and I think he'd always imagined what it'd be like to walk out to them. It's such an iconic song, and he liked that the drums were in there," said Brian.
"I knew the original very well because I grew up with the Gay Byrne theme, and I knew that Ryan wanted the old theme but with something new at the same time."
Brian described it as an "honour" to be asked to compose the tune to the longest-running chat show in the world.
He said: "My father called me up on the first night and he blasted it loud over the phone which was a thrill."
Brian had built up a good relationship with Tubridy since the presenter started work on Radio One.
He said arranging the Late Late signature music took him two days to record and then two days to mix. He approached the project by trying to develop a 'retro-style' signature, evoking memories of the original music from Gay Byrne's time, while giving it a modern jazz twist.