When two biology teachers from opposite sides of the world agreed to swap jobs, homes and hemispheres for a year in 1996, they knew that a few professional challenges lay ahead. What neither of them could have foreseen was how the exchange would transform their family lives and their marriages - for better and for worse.
For Keith Brook, a teacher at Birkdale School in Sheffield, the chance to spend a year in New Zealand was not to be missed. A keen enthusiast of the "great outdoors", he found the lure of the South Island's spectacular scenery and open spaces irresistible. His only concern was how his family would cope with being uprooted - his wife, Gillian, had never ventured further afield than north Wales, and his two sons, Jamie, nine, and Nathan, 10, were settled and happy at school.
He needn't have worried. They all adapted quickly to a new and very different style of living, and they all fell in love with New Zealand. More importantly, they rediscovered the joy of spending time together as a family - something their lives in England had made impossible.
"Everything we did was done as a family unit," says Keith. "Back home our lives had become cluttered and crowded. Commitments had built up over the years - work, parents' associations, church groups - and without us realising it, our family life had just disappeared."
Not that teaching in a new environment didn't bring heavy demands. Burnside high school in Christchurch was much larger than Keith was used to - it's the largest in New Zealand, with more than 2,000 pupils - and the children less academic, more unruly.
"I realised I'd become complacent and a little lazy in my teaching. For the first time since training as a teacher 20 years ago, I was forced to take a close look at my methods and my classroom management skills. I had to adjust to a lack of technical resources. There's no doubt it's made me a better teacher."
But it was their experiences out of school which made the year so memorable. Far from trying to recreate the "normality" of their English lifestyle, they grabbed every spare moment to explore as much of the country as they could.
"By day we were residents. But once the bell went for the end of the day, we were tourists enjoying the holiday of a lifetime."
It was an approach that Keith's new colleagues found bemusing. "One night after school, we headed off over a mountain pass to see some natural springs. It was a tortuous journey and a very, very late night, but it was an amazing sight. Unforgettable. When I mentioned it in the staffroom next day they all thought we were mad. None of them would have considered the journey for a full day out at the weekend, let alone on a weekday evening."
Driven by this spirit of adventure, every Friday evening the family loaded up the car and headed for the wilds. The holidays offered scope for even more exciting travel, including two weeks of kayaking down a remote stretch of coastline and camping on deserted beaches.
At the end of the year and back in Sheffield, they were determined to keep alive their new-found family bond and zest for life. They cut back on their commitments - "after all, life seemed to have gone along very nicely without us". They also designated one evening a week as "family night"; a night when Keith was banned from bringing work home so the family could go on an outing or join in an activity together. Swimming at their local pool or taking a drive out into the Peak District might not compare to surfing the Pacific Ocean or traversing perilous mountain passes, but the principle has stayed the same. And summer holidays are now earmarked for major expeditions: this year they have Nepal in their sights.
"Ichanged our lives. As simple as that. We have different horizons now, different priorities. It's become so much easier to leave the pressures of the classroom behind at the end of the day. But it needed a complete break from routine to show me how it could be done."
It all sounds very exciting and heart-warming, but before you rush down to the League for the Exchange of Commonwealth Teachers and hammer on their door demanding your own personal life-changing adventure, consider the story of Roger Stoutjesdijk, the Christchurch teacher with whom Keith Brook traded places.
"The exchange cost me my marriage," he says frankly. "At the time it was a nightmare." The first shock came when he realised the timetable he had inherited from Keith included plenty of A-level biology teaching - which he wasn't accustomed to - and some of the groups were very able. While Keith had been able to "dumb down" his lessons without too much trouble, Roger was faced with long evenings frantically digesting textbooks and curriculum documents. "It was a different type of school, more academically oriented. I felt a little intimidated and my confidence suffered. It was like I was back at college, swotting up for a couple of hours every night on top of all the marking I had to do. It was exhausting. I was shattered."
Roger's relationship with his wife suffered. Whereas Gillian Brook gave music lessons at her sons' school, Roger's wife, Susan, spent long hours on her own at home. "It was difficult for her," he says. "I was the one who'd been keen on the exchange, and I'd talked her into it. But, while I was out at work she was stuck at home - a stranger's home, remember - with no friends or support. Then, when I finally arrived home each afternoon, I'd shut myself away and start working. It was very difficult.
"Also, the exchange ran January to January, so we were flung from a warm New Zealand summer into a pretty miserable English winter. I know it sounds lame to moan about the weather, but if you're feeling a bit down it doesn't help your mood.
"Christchurch is a big city, but it's quite laid back. The pace of life seemed more frantic and stressful in Sheffield. We both liked the Derbyshire countryside, which was on our doorstep, but we didn't have much time to explore it. And I missed being near the sea."
Roger in no way blames Birkdale and says he received plenty of moral support. None the less, the combination of a strange country and a new job at times left him feeling like an outsider.
"People were good to me. The staffroom was friendly, but you feel a bit of a novelty. I was always the visiting Kiwi. It's hard to feel integrated into a school when you know you're only there for a year."
It all became too much for Susan and she flew back to New Zealand, even though she had no home to return to. Roger now faced the challenge of keeping his marriage alive with his wife more than 11,000 miles away. "My heart told me to get on the next plane; my head, and my headteacher, told me I had a job to do in England - responsibilities to the school and to the pupils - and I had to stay focused on that."
Roger and his wife were reunited when the year ended, but divorced some months later. Now rebuilding his life, he is able to look back on his time in England with a certain fondness.
"There were difficult times, sure, but plenty of special times too - precious memories of people and places. I'd still recommend an exchange to anyone. Besides, who's to say my marriage wouldn't have had troubles even if we'd stayed in New Zealand?" Keith and Roger still keep in touch by e-mail. It seems strange to them that though they lived in each other's homes for a year, and have two staffrooms full of mutual acquaintances, they have never met. But, as Keith Brook points out, there is a bond between them that comes from their shared experiences. "You definitely come out of an exchange year