Gavin Cooper at Queensland Origin camp.

He may have been the butt of jokes up in Townsville but Gavin Cooper is quick to point out that he wasn't the oldest player invited to Queensland's Emerging Origin camp in January 2015.

Surrounded by the state's brightest young talent, Cooper and Manly's Brenton Lawrence stood out as proof that age counts for nothing if you are delivering on the football field but the likelihood was that both had left their Origin runs too late.

But a premiership with the Cowboys and experience as 18th man in Game One of this year's Holden State of Origin Series meant that when Queensland selectors needed to find a replacement for the injured Josh Papalii, 30-year-old Cooper was the man that they called.

With his wife Tenille having given birth to the couple's second baby boy on Tuesday Cooper finally linked up with the Maroons on Thursday morning and completed the first training session of the week.

Now in his 11th season in the NRL, Cooper participated in the captain's run prior to Game One with the injury cloud that was hanging over halfback Cooper Cronk and believes that experience will make for a smooth transition into the Origin arena next Wednesday night.

"I wasn't the oldest one in the camp so I was pretty happy with that," said Cooper.

"It goes to show if they think you're the right man for the job, it doesn't really matter.

"People keep talking about age and bringing in the new crop of players but this team has proven it's just a number.

"You can't buy the experience these boys have got. There are boys in here with over 30 Origins.

"'JT' (Johnathan Thurston) has played 36 straight, 'Smithy' (Cameron Smith) has got the record, 'GI' (Greg Inglis) is about to play his 30th and Nate [Myles] is there as well.

"The bond and culture that's been built up here for a long time, you feel it straight away.

"It's something I'm grateful to be a part of and will never forget.

"Being in that camp (prior to Game One) might have given me a bit of a leg-up to know what to expect."

Cooper's Cowboys teammate Matt Scott admitted he was one of the people teasing the then 29-year-old of his 'emerging' tag last year but that his demeanour and team-first ethos fitted in seamlessly with what the Maroons have built up over the past decade.

"I think he was the first 30-year-old Emerging player to be named but it was very light-hearted and we all know that it's probably just unlucky more than anything that he hasn't got his opportunity before now," said Scott, who will play his 22nd Origin game for Queensland on Wednesday night.

"He really suits the team culture and the camaraderie that we've got here. We've already seen when he came in for 18th man he just slotted in automatically like he'd been here for the last 10 years.

"One thing we've been able to do with this team and the culture is to bring guys in and make them feel automatically at home and he's no different.

"He already knows a lot of the guys, he's been around for a long time and he's good mates with a lot of the fellas.

"He really typifies the type of player that has been able to come into Origin sides and do well."

Showing just what a doting dad he is, on his first day in camp as Maroon No.185 Cooper was already thinking about a quick return trip to Townsville to spend more time with Tenille, two-year-old Archie and the Cooper family's newest addition, Reggie Mack.

Once Cooper got the word that he had been selected to play in Game Three Tenille's scheduled delivery date of Thursday was brought forward to Tuesday, giving him crucial extra time to prepare for one of the most significant games of his life.

"As excited as she is it is a little tough on her being in hospital. I think I owe her a bit," Cooper conceded.

"It was a bit tough leaving the hospital this morning before I came down here knowing I've got a two-year-old as well that needs to be looked after.

"Tenille understands and knows this great opportunity I've got. She's pumped for me.

"We were always booked in but not for Tuesday, we had to bring it forward a few days.

"I didn't want to miss the time in camp with the boys to build towards something special.

"We were fortunate enough our obstetrician helped out as much as he could.

"He really helped with our planning. He knows the opportunity I've got.

"We're very grateful for him."