So he filled out the online application, which included making a short video of himself, and did his first audition via Skype.
"Then I got to the second audition and then the third audition and then I got the word that I was in."
There was nothing in the way of nerves at that stage, just "pure excitement", and he embarked on his swotting campaign for the subject he had chosen - American history during the 1960s.
"History is my thing - the 20th century," Mr Barnes said.
Subjects such as World War I and World War II were too big - too expansive, so he focused on 1960s US.
Part of the deal is an agreement with the production team that two reference books can be used for him to work from. From those books, the question-making crew create their questions.
"You have to commit a lot of time to it and I had a quota (of research) every day which I worked in around school work.
"It was a real challenge but I'm pretty organised - I know how to study."
The filming took place at Easter.
He was one of 32 people now lined up for the series, in groups of four, and when he took his seat to face host and quizmaster Peter Williams it was "seventy per cent excitement and thirty per cent nerves".
Among the small audience group were his parents, wife, sister and a couple of friends - but he could not see them when the "action" began.
"You do become focused because you're in the chair and all you see is the spotlight and Peter Williams - everything else is just darkness."
He said Mr Williams was a "real gentleman and a great host" and helped smooth the way for the contestants.
Mr Williams is not at liberty to say how he got on, of course, but expects to get plenty of reaction after his segment is screened - especially when he gets back to school.
"Oh no ... pandemonium," he said with a laugh.
His advice for anyone keen for a very public challenge in possible series to come?
"Oh yes, give it a go."
