Long serving Roos captain Peter Nau announced late last year he would be moving to Sydney to test his talents but his position hasn't remained open for long with Tremain opting to join the Blowes Cup premiers after moving to Dubbo for work.

The signing comes as a huge boost for the Roos with the likes of Nau, Max Ma'a Nelson, Anthony Golding, Brad Pugh, Enoch To'Ofohe, Tim Cullenward and Scott Burgess all not playing in 2015.

Tremain, who captained Orange City for several years and was the heart and soul of the first grade sides since 2004, said after speaking with people at the Dubbo club he imagines he'll slot in for Nau.

"I've spoken to the guys at 'Roos, and that's the plan," he said.

"It's a bit disappointing I was hoping to play with Pete (Nau) at club level, but it opens up the hooker position, and I think they're looking for me to fill that spot.

"I've always thought I play my best rugby at hooker, even though they're big shoes to fill. I know there are some older guys at the club sticking their hands up again, it looks like while 'Roos are losing a few the side will still be very strong.

"I'm actually really looking forward to training starting next week."

Former NSW Country Cockatoo Tremain spent 10 years with the Lions, recording two undefeated premierships, a grand final loss and countless priceless moments in the Orange City colours and admitted it was an hard decision to leave the Blowes Cup powerhouse but the prospect of travelling back and forth two, three and even four times a week to remain a Lion was too much.

"I felt like I wouldn't be able to give City my absolute best efforts, which wouldn't benefit me or them," Tremain said.

"It was an incredibly tough decision to make, I love Orange City and wish I could stay there forever, but I needed to move on for reasons outside rugby.

"A few of the younger guys were disappointed when I told them, but the more senior guys understood as did the club members. I hope there isn't any bad blood from anyone, and I doubt there will be."

Tremain is set to meet his now former teammates at Orange City in round two, at No.1 Oval, but won't return to Pride Park until round 11, on July 4, in the return fixture.

"It'll definitely be interesting the first time I play against Orange City, I'm sure there will be a fair bit of banter from the sidelines," Tremain laughed.

"It will be good though, the whole thing is a new challenge for me. I've always found when I go to a new environment, or team, or different level it brings out my best rugby.

"Hopefully this is a chance to freshen up, and play some really good footy for the Roos."