But fans wondered where they were and if they would arrive later in the series.
The couple were teased on Tuesday’s show, arriving at Gwrych Castle just three days after the start of this series, which is shorter this year at three weeks.
They join TV presenter Vernon Kay, broadcaster and journalist Victoria Derbyshire, stage and screen star Shane Richie, Paralympic gold medalist Hollie Arnold MBE, Radio 1 DJ Jordan North, icon of Corrie Beverley Callard, ballroom dancer AJ Pritchard, author and podcaster Giovanna Fletcher, Olympic legend Sir Mo Farah CBE and soap star Jessica Plummer.
Ruthie said, “There’s a big difference between the known and the unknown, and I’m in the unknown.
“It’s really a little scary.
“Coming in late suddenly feels a lot more exposed, you have to bring something to the table.
“I think I’m a tough cookie, but I’m a little terrified. “
Russell added, “I’m probably best known for my performances as Nessun Dorma, but they’re going to see a different side of Russell Watson.
“The stage is the blood of my life, it means everything.
“I don’t think it’s going to be fun at all, I don’t even want to think about the bugs right now. ”
Ant McPartlin and Dec Donnelly have revealed that the duo will take part in a trial called Stage Fright before meeting the rest of their campmates.
* I’m a celebrity airing weekdays on ITV at 9 p.m.