New Year'S Eve, 1983. Two aspiring New Zealand actors, Erik Thomson and Rebecca Gibney, spent the night partying with thousands of other drunken young revellers at Mt Maunganui. But, they never met. "At least, we don't think we did," laughs Thomson. "But we have worked out that we were both there."

Fast forward more than a quarter of a century and the pair are united in a very different way, playing a married couple in the top-rated Australian television series Packed To the Rafters. Both actors have risen to the top of their professions across the Tasman. Their paths could have crossed again in Wellington, where Gibney lived and Thomson went to in 1985 to attend Victoria University and drama school. But by then Gibney, a couple of years older, was already on her way to Australia.

Now both actors have young children, as opposed to their on-screen characters, who barely had time to enjoy their calm and quiet empty nest before the "baby boomerang" phenomenon led to their three children (and one parent) returning home with wounded pride, empty wallets and bags full of dirty washing.

In Tuesday's season finale, however, they have to decide whether they'll proceed with a shock pregnancy which Julie (Gibney) had initially mistaken for menopause. Thomson, who was born in Scotland before moving to New Zealand at the age of 6, can't quite believe where the time has gone. "This is my 19th year since leaving drama school. I guess that means I'm a professional actor now. This is what I do."

Now, instead of being the hopefuls from New Zealand, he and Gibney are the veterans on the set of Packed to the Rafters. "As the 'heads of the household' we've tried to instil a work ethic," says Thomson. "It can get quite gruelling. With us older actors, these 5am starts begin to show on your face a bit more." Thomson started acting on stage for various New Zealand theatre companies, before landing roles in the "swords and sandals" series like Hercules and Xena – "like every other New Zealand actor. Although I didn't do Shortland Street. I've kept that up my sleeve – you never know."

Inevitably, in his late 20s, he followed the well-trodden path to Australia, seeking more opportunities. "I felt I had to come over here," he says. "I love New Zealand and I loved working there, but I could see the ceiling and I was starting to hit my head on it after just five years out of drama school."

Perhaps best known here for his roles in The Alice (inexplicably canned after one season), and his starring role as Dave Henderson in the film We're Here to Help, 42-year-old Thomson has thrived in Australia, winning a Logie award and an Australian Film Institute award for his many TV and film roles, and twice being named Most Popular Personality on Australian TV.

Packed To The Rafters was the Seven Network's highest rating series last year. Described by some as a "dramedy" – Thomson prefers to think of it as "a drama with lighter moments" – the programme has struck a chord with audiences who can relate to the advent of the baby boomerang generation, a trend for adult children to return home, exacerbated by the high cost of buying houses and the recession. He says the timing of the show has been fortuitous. "I think this is a show of its times. It's hit the nail on the head. "That could be the reason for its success – people can identify with it. We have been fortunate in that we've tapped into the times, which are people finding it tougher and having to pull together. A lot of people out there can understand it."

Thomson managed to avoid a Rafters situation for most of his early career, although there were times when he and his wife Caitlin moved in with her parents for short periods. And he doesn't necessarily see the baby boomerang situation as negative. "In many ways it would have been nice to not have the pressures. It certainly makes life easier."

However, in the television show it is the pressure-cooker of cohabitation which is the source of the comedy – and the drama. The writers have not shied away from dark themes, such as domestic violence, poverty and bereavement. Thomson's character lost his job in the first episode, a scenario many New Zealanders can relate to. "I think of it like a family Christmas Day, every day. There is always some undercurrent, reminders of ghosts in closets. To borrow a cliche, it's about keeping it real. As soon as we lose touch with reality, we are stuffed."

Thomson has completed a second season, with another in the pipeline for next year. He also features in the recently released in Oz film The Boys Are Back by Shine director Scott Hicks, and enjoys being a father to 2-year-old daughter Eilish. He agrees Australia has been good to him. "I've had a very full, varied and busy 20 years. Life is good. I'm not complaining." He refers to New Zealand as his "spiritual home" and most of his family is based here. He's hoping to be back for Christmas, possibly with his sister in Auckland's Remuera. A trip to his hometown Tauranga is also on the cards. And a big New Year's Eve at the Mount perhaps? Thomson laughs. "Those days are definitely gone!" Packed To The Rafters' season finale plays on TV One, Tuesday at 8.30pm. Repeats screen weekdays from Wednesday at 2pm.