Watch: This Morning celebrates 20 years of Phillip Schofield with flashback
Schofield, 60, began Tuesday's episode of the ITV daytime show with a look at his first time on air there, 20 years ago to the day and when he had just joined Britton as John Leslie's replacement in 2002.
His current co-host, Holly Willoughby, said: "Well, we couldn't start today's show without mentioning something very special - it really is a huge achievement."
Although Schofield said he hadn't realised it was his 20th anniversary until the show's bosses flagged it up to him, he was soon reminded of his This Morning debut with the throwback clip.
A youthful-looking Schofield was shown with brown hair rather than the silver locks he is known for and sitting alongside Britton as she introduced him to viewers.
Show contributor Vanessa Feltz also appeared in the clip as they chatted about I'm A Celebrity...Get Me Out Of Here! which was airing its first series at the time.
Britton hugged him as the show finished and he told her: "That was fun."
After watching the clip, Schofield said: "Oh my god, I don't think I've ever seen that."
Willoughby told him: "You know what's so weird about that, seeing you as the new boy. That's so weird because it feels like you've been here forever."
Schofield replied: "And I was nervy as well. But Fern was so lovely to me, looking after me."
Willoughby said: "That's what you were like with me on my first day."
This Morning hosts Schofield and Willoughby have been working together since 2009, with Willoughby replacing Britton who left after a row over Schofield being paid more than her and accusations that he was meddling in editorial content.
They had an awkward reunion in 2018 when Britton appeared on the show via video link to congratulate Schofield and her successor Willoughby on a Bafta recognising the show's 30 years on air.
Britton said: "Congratulations on Bafta. That was absolutely wonderful and brilliant, and I would have loved to have been there, but I didn’t get an invitation..."
The row also spilled over onto Twitter afterwards as Schofield tried to insist she had been invited, although Britton was adamant she hadn't been.
On Tuesday's episode after watching the flashback clip, Schofield joked: "I haven't heard anything about the audition so that's why I keep rocking up.
"No one's ever told me I've actually got the job."
He added: "I never forget how lucky I am, so thank you very much."
Watch: Phillip Schofield and Kelly Holmes cry as they discuss coming out experiences