Sullivan reprises his performance in the role, which he has previously played on tour.
Gaumond joined the cast of We Will Rock You last August having been nominated for both Whatsonstage.com and Olivier Best Actor in a Musical Awards for his performance as Elle Woods’ Harvard Law school squeeze Emmett in Legally Blonde.
He will play his final performance in the role on Saturday 18 February 2012, leaving the show to "focus on his recording career."
Noel Sullivan came to prominence in 2001 as a member of Hear'Say, the first TV talent search band, formed from the winners of ITV's reality show Popstars.
His stage credits have included roles in Fame, Grease, Love Shack, Flashdance and Simply Ballroom. He also took part in the Royal Gala opening of the Millennium Centre, Cardiff in his native Wales. Sullivan played Galileo over 300 times as part of We Will Rock You's national UK tour.
We Will Rock You have also today (31 January 2012) announced that the production will continue to run throughout the London Olympics, playing a normal performance schedule throughout July and August 2012.
The musical has a book by Ben Elton and features 32 of Queen’s greatest hits including "Bohemian Rhapsody", "Crazy Little Thing Called Love", "Under Pressure", "Radio Gaga" and, of course, "We Will Rock You". It’s directed by Elton, choreographed by Arlene Phillips and designed by Mark Fisher and Willie Williams.