Cat Deeley reunites with Ant and Dec on a rebuilt SM:TV film set 18 years after leaving the show as the duo help to promote her new children's book

She fronted the Saturday morning ITV show with the famous duo from 1998 until 2002, and recently confirmed a special reunion show had been filmed.

And, Cat Deeley, 43, reunited with Ant McPartlin, 44, and Declan Donnelly, 44, on a rebuilt SM:TV film set, 18 years after they left the show.

Ant and Dec took to their Instagram account on Tuesday evening to share a group shot, as the duo helped to promote her new children's book The Joy In You.

Reunited! Cat Deeley, 43, reunited with Ant McPartlin, 44, and Declan Donnelly, 44, on a rebuilt SM:TV film set, 18 years after they left the show

Earlier in the day, Cat jokingly stormed off during an interview with This Morning when she was shown her first ever screen test with Ant and Dec. 

The red-faced presenter left her seat and walked out of shot, but it was all done in good humour.    

Talking about the reunion show, Cat said: 'We shot a documentary and we talked about all different things, how we first got together how we first met each other, all the things that went wrong in the show.  

'It was at a time of our lives when we didn't have many responsibilities really, it went quite badly at the beginning, but we turned it around, we found our feet. We found the chemistry between us.' 

Helping out! Ant and Dec took to their Instagram account on Tuesday evening to share a group shot, as the duo helped to promote her new children's book The Joy In You

Now and then: She fronted the Saturday morning ITV show with the famous duo from 1998 until 2002, and recently confirmed a special reunion show had been filmed

It comes after Cat confirmed the SM:TV Live reunion show had been filmed - and teased an air date.

The presenter told The Chris Moyles Show on Radio X that the series will be looked back on in a special documentary, to be aired at the end of the year.

'I can confirm… yes.' Cat teased, when asked about it by Chris on the air. 'We have filmed a documentary, it's going to be aired at the end of the year.

'We went back to the studio where we did it. They rebuilt the set. We all cried. I walked in and Ant & were doing their interview and Dec was crying and I was like 'ok you're crying!' and then at the end of my interview I was like 'waaah!'

Best friends: Ant and Dec have remained firmed friends and presenting co-hosts, while Cat jetted off to the US where she forged a solo career

They're back! It comes after Cat confirmed the SM:TV Live reunion show had been filmed - and teased an air date (pictured in 2008) 

'We all have a bit of a cry, we take the mickey out of each other, it's very, very, very cute.'

She revealed that Ant & Dec have seen the show already, continuing: 'I actually got a text message from Ant yesterday saying he's seen the first cut and they cried watching it too.' 

SM:TV Live ran for more than 270 episodes from 1998 to 2003 with Ant and Dec at the helm for the first three years.

It was then hosted by Steps stars Ian 'H' Watkins, 44, and Claire Richards, 42, between 2002 to 2003. 

Sweet! 'We all have a bit of a cry, we take the mickey out of each other, it's very, very, very cute' said Cat of the reunion show (pictured in 1998)  

Cat moved Stateside 14 years ago to focus on her career with husband Patrick Kielty, with whom she has two sons, Milo, four and James, two, but recently returned to the UK full-time after putting their £4m LA home up for sale.  

Since 2006, Cat has presented the competition show So You Think You Can Dance in the US, and been nominated for five Primetime Emmys.  

Speaking about her move to the US, she said: 'I think the thing that would surprise the young me about her future is what's happened in America.

Stateside success: Since 2006, Cat has presented the competition show So You Think You Can Dance in the US, and been nominated for five Primetime Emmys (pictured in August 2018) 

'I mean, I never went to America when I was a kid. I never went to Disneyland or anything like that, I'd never even seen it before.

'And when I did go, I never made a great proclamation: 'I'm going to crack America.'

'A relationship had just ended and I just fancied a fun adventure. It did feel crazy at times... There's no way my 16-year-old self would believe me if I went back and told her she'll be there one day.'

Messing around: Red-faced Cat Deeley 'stormed off' during herThis Morning interview  on Tuesday when they played her first screen test with Ant and Dec ahead of SM:TV reunion