"Our show of friendship is probably what you see in the first show", continued Simon - talking about the first episode of the new series, which will be aired on Saturday night.
Ant, 42, has returned to rehab after being involved in a three-car collision in London, where he was arrested at the scene on suspicion of drink-driving after failing a breathalyzer test.
In a heartfelt moment, Spelmann said the real magic was the birth of his daughter, who was born through IVF, as he shocked the audience with the trick which involved a video of his child matching choices the judges had made.
The presenter was seen laughing and dancing in the episode, and was close to tears as Spelmann's trick played out.
Ant will continue to feature in the audition stages of the show but his other half Declan Donnelly will be presenting the live semis and grand finale without his pal.
"You got me in tears, man - remarkable", McPartlin told the contestant.
An escapologist, a magician and a dance troupe set up by former Britain's Got Talent victor Ashley Banjo all feature in Saturday night's episode which sees Simon Cowell, Alesha Dixon, David Walliams and Amanda Holden return as judges.
Amanda Holden told him the performance was "utterly extraordinary" adding: "We're all parents and that is the greatest magic in the world, ' - but before they could take a vote Ant and Dec headed down to the judges" desk with Ant declaring: 'You don't have to vote!' before the pair hit the Golden Buzzer.
Meanwhile an acrobat who was labelled "boring" by Cowell prior to his audition will redeem himself according to Walliams, who called it the "most thrilling two minutes we've ever had on Britain's Got Talent". He is due to appear in court on April 16.
Britain's Got Talent begins tonight from 8pm on ITV.