Holly Willoughby was left cooing over Phillip Schofield in a 35-year-old clip from children's BBC show The Broom Cupboard.
This Morning presenter Phil, 60, had been in his 20s when he appeared on the show with Gordon The Gopher.
Teasing that they had a "very special" show for viewers, Holly said that the show would be taking a special trip down memory lane.
A short clip airing showed Phil without his characteristic silver hair, instead sporting fluffy hazel locks, and wearing an oversized green and blue sweatshirt as he sat beside Gordon.
"Have you seen his jumper?" Phil was heard saying as he pointed to Gordon. "If you look at his jumper, it says 'I'm with the idiot' on here. Look - that's not very fair, is it?! I'd like one myself, actually, but I didn't get sent one of those. Sometimes I think you're taking over!"
As Gopher squeaked, Phil jokingly demanded: "Don't you shout at me young fellow!"
Laughing after the clip aired, Phil said: "Oh my!"
"He's the cutest thing," Holly gushed. "You are little Phil! As the BBC turns 100, we're taking Phillip back to his Broom Cupboard days - not quite as long as that! As he's reunited -"
"Feels like it sometimes," Phil quipped.
Giggling, Holly continued: "- with the channel's other famous presenters and finally, the gopher. Hi Andy and Andi!"
Andy Crane and Andi Peters had joined This Morning today to reunite with fellow Broom Cupboard presenter Phil.
Phil had presented the show from 1985 until '87, followed by Andy Crane from '86 until '90 and Andi from '89 until '93.
Other famous faces who hosted the programme included Philippa Forrester and Toby Anstis (1990 to 1994), Zoe Ball (1993 to 1995) and Jose D’Arby (1994 to 1997).
*This Morning airs weekdays at 10am on ITV
