The royal trio watched intently as students produced the show from a desk covered in buttons, switches, lights, as senior producers supervised their efforts.
The presenters were behind glass in a studio and William joked: "Funny thing to be locked in a box talking to a big red microphone."
While Theakston quipped: "I'm not sure the royal party has been this close to a Spice Girl."
"I actually approved the planning of this site when I was the cabinet member for planning," said the outgoing mayor.
"It's nice to see the project come from a 2D vision to seeing it here today in 3D.
"What has been identified is that there is a skills shortage, not just in the media but replicated across professions from builders and plasterers to engineers.
"If the country is going to develop you need to have proper apprenticeships and skills training.
"To extent this school addresses that imbalance."
The royals were treated to poetry from year 10 pupil Ash Chouhan, from Ruislip , as well as a short film produced by a student and a dance performance.
After the performances, Global's executive president and founder, Ashley Tabor, unveiled the microphone commissioned for the princes' great-grandfather King George VI, popularised by the blockbuster film The King's Speech.
The microphone, unveiled by the Duke of Cambridge, was discovered in the EMI archives, and used to symbolise Hayes' media legacy.
The school is pioneering mental health awareness in education by having an hour of mental wellbeing sessions every week, where pupils can discuss their mental health with staff and each other.
Global Academy's principal, Simon Collins, said: "The students we've got are absolutely phenominal.
"They are so passionate and they really go above and beyond.
"Unlike some schools where the bell rings at 3.15pm and the students run out, we have kids staying here right up until 7pm, until the caretaker kicks them out!
"I think we are the first of a big change to Hayes, we are only going to be a good force here."
The Cambridges and Harry have been championing their Heads Together campaign which encourages the nation to talk openly about their mental health and offer a sympathetic ear for others to do the same.
On Wednesday, Harry commented on his decision to speak out about the issues he faced after his mother's death, saying it was "only right" he aired his experiences as he wanted to encourage others to "smash that stigma" around talking about mental health.
He was praised by the duchess, who described him as "brilliant" for revealing in an interview with the Daily Telegraph that he spent nearly 20 years "not thinking" about the death of Diana, Princess of Wales, and eventually got help after two years of "total chaos".
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