His career has gone from strength to strength in the intervening years, whilst his three year marriage and toddler daughter Missy are proof that the 27-year-old is definitely now all grown up!
In an interview with this weeks New! mag Gareth spills the beans on his marriage to 36-year-old Suzanne, and talks about what sort of dad he is to his adorable little girl, three-year-old Missy.
And whilst he won't comment on the allegations that he had an affair with his former Les Misérables co-star Katie Hall in 2010, he does admit that his three year marriage hasn't always been easy.
He reveals that he and Suzanne 'make time' to keep the romance alive in their relationship, 'fessing up that it is 'quite hard at times, if I'm honest'.
"But we're very much family people," he says, "So being at home together with Missy is what we love."
And although he adores being a daddy, he doesn't have any plans for more children:
"It's great. Missy's three now. She's lovely most of the time, but some of the time she's a right nightmare. Being a father is scary. I've always wanted a big family but after the one, we're just... It's much harder work than we thought."
Gareth says he is a very hands on daddy - getting 'massively' 'stuck in' and trying to get home as often as he can between performances. And those spells in Joseph and Les Misérables appear to have had an effect on his little girl, who is apparently a chip off the old entertaining block.
"She's already singing and dancing," her proud dad says, "We have a fireplace at home and
it has a platform that she calls "Missy's Stage"!"
And like most daddies with their girls, Gareth is very protective of his little daughter!
"I vowed never to be as protective as my dad, but having your own child you instantly think differently!" he admits.
Do you reckon he'll change is mind about having more babies - 28 is very young to say never again!
Read the full story in this week's new! magazine - out today