"I didn't think I'd get past the first round," Setterfield said afterwards

The 37-year-old, from High Wycombe, Buckinghamshire, has earned a three-month contract to appear in a high-profile stage show in Las Vegas.

She has already toured the world while performing as the late Springfield, and described how she had been "obsessed with music" throughout her life.

"I'm gobsmacked," she told host Graham Norton. "I really can't believe it."

The programme's original 12 contestants had been whittled down to five for the final.

Setterfield was up against Anthony Adams (Frank Sinatra), Joanna Berns (Cher), Tony Lewis (Robbie Williams) and Moni Tivony (Lionel Richie).

Berns and Lewis were eliminated first, and then viewers' votes put Setterfield in first place, followed by Adams and Tivony.

You're crazy, but that was the best vocal performance of this entire series Vocal coach David Grant

Setterfield won praise from the show's vocal coaches and mentors.

After hearing a rendition of In the Middle of Nowhere, coach Carrie Grant said Setterfield was able to "make it look too easy".

"That is what you want when you sit for 45 minutes and watch a show in Vegas. You want to be entertained - it needs to look easy."

Fellow mentor David Grant said Setterfield's choice of All I See is You was "the most high-risk performance".

"[It was] the biggest song emotionally, the biggest song in range and you choose to sing it in the final.

"You're crazy, but that was the best vocal performance of this entire series."

Setterfield said she was "very excited" about going to Las Vegas and appearing in Legends in Concert, which has been billed as the world's long-running tribute show.