Author and celebrity Amanda Brunker has defended her right to play at Oxegen despite consternation from many music fans.

Brunker will feature on the prime slot at 2pm on Saturday afternoon after British singer Jessie J was forced to pull out because of a broken foot.

She will duet with Gitano, a band fronted by Irish-based Spanish guitarist Francisco Garcia on the Vodafone stage, the second biggest at the festival.

Brunker recorded a number of songs with Gitano a few weeks ago and emailed MCD promoter Denis Desmond about appearing at Oxegen.

She confessed to being flabbergasted that Desmond emailed her back to confirm her presence on one of the two main stages, where she will be followed by household names including Imelda May and Paulo Nutini.

“I know people think this is a joke, but it is not at all,” Brunker said. “We’re definitely on. There is no backing out of it as this stage. I’ve started as I mean to go on. It’s quite terrifying.”

Brunker said she could understand why people did not take her seriously as a singer. “I’m no Beyoncé,” she said.

Her appearance has caused a storm of protest on social media outlets and on blogs.

Irish Times music writer Jim Carroll said the “mind boggles on so many different levels about this news” when so many Irish acts could have benefited from such a slot.

Similar sentiments were expressed by contributors on Carroll's On the Record blog and on Twitter and other music sites.

“Why shouldn’t I get a chance?” retorted Brunker. “As far as I’m concerned, there are always people out there who want to have a go. At the end of the day I don’t like to just talk about doing things. I like to go out and do things. I believe there are limitless possibilities of what we can be and this was on the list. What little girl hasn’t dreamed of being a pop star?”

Brunker said Gitano “are serious musicians” who played Oxegen in 2009 and have played to capacity crowds in the National Concert Hall.

Garcia said the public would be “very, very surprised” by Brunker’s singing. “For somebody who has not been in the business, she has done a great job,” he said.

Her set will feature a cover of U2’s With or Without You and other covers. Though she and Gitano have been allocated 50 minutes, they will not have enough material together to fill the slot.