DERMOT O’Leary shocked This Morning co-star Cat Deeley when he revealed his real name on the ITV show.
The 51-year-old made the revelation during Tuesday's instalment of the breakfast programme.
An intrigued Cat, 48, was interested to know if her co-host has a middle name.
Dermot said: "My first name is Sean, Sean Dermot O'Leary."
Cat - who has known Dermot for over two decades - replied: "Your first name is Sean? How did I not know that?!"
She is married to fellow TV presenter Patrick Kielty, who is from Northern Ireland.
Dermot asked Cat if her husband's first name is actually Patrick, to which she confirmed that it is.
He then told Cat: "Okay, well, normally, if you're born in Ireland or if you have Irish parents, they name you something, and then they call you something totally different.
"So, I am Sean Dermot, but I've only ever been called Dermot.
"But I'm officially Sean Dermot."
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Over the years the broadcaster has had some awkward encounters, including one at the passport office.
Dermot recalled: "Once, I went into the Irish passport office. Pre-Brexit, the Irish passport office was quite chilled, so they were like, 'Oh yeah, you're here, we've got your passport.
"I looked down, and it said Dermot.
"They went, 'Yeah, you are Dermot?'
"I said yeah but I'm also Sean Dermot, look at the old passport."
"So, now I'm both Dermot and Sean Dermot, which, as you can imagine, for legal reasons, is quite confusing!"
The This Morning favourite was born in England to Irish parents, Seán and Marie.
Dermot grew up in Colchester, Essex, alongside his older sister Nicola.
He was named after his father - Seán Dermot Fintan O'Leary Sr - but with "junior" at the end.
The star joined the This Morning team to present Fridays and holidays with Alison Hammond back in 2021.
However he stepped in this week Ben Shephard as he filmed a new game show.
Ben has already jetted off to New Zealand where filming will take place, after announcing his mysterious break from This Morning last week.
An insider said: “Ben was the perfect choice to host the UK version of the popular format, given his own interests in fitness and sport as well as hosting Ninja Warior for six series.
“He sat down with his bosses on This Morning who have known for a while now and allowed him time off from the sofa to film The Summit.
“The programme has been kept top secret to avoid spoiling the format and what’s in store for the contestants, who are now all on their way to New Zealand.
“Bosses are hoping it will produce good old-fashioned nail-biting reality TV moments with back-stabbing and strategy, coupled with physical endurance.”
On Monday Dermot shared a snap of him and Cat on the sofa, alongside a picture of them from 24 years ago.
He wrote: "First time presenting @thismorning alongside the wonderful @catdeeley …
"But these paths have crossed before.
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"Here’s a 24 year throwback to 2000. Dx."