Is teaching overseas something you do when you're young, a way of globetrotting and getting paid for it? Or can you make a career out of being an expat teacher? Tristian Stobie has certainly given it his best shot. He has spent the past 18 years teaching in international schools in Lesotho, Vienna, and Monaco, and has worked his way up from classroom teacher to become a high-school principal at the American community school, an international school in Egham, Surrey.
And he hasn't looked back. He is a strong advocate of the International Baccalaureate programme used in many schools across the world, and believes it is far superior to the national curriculum in the UK.
Mr Stobie, 43, says he has had more professional development as an international teacher than he did as a class teacher in Berkshire. And he believes international schools now have a robust career structure of their own.
"I have no intention of going back to either the private or the state system in this country," he says. "The reason is professional stimulation.
I find working with a framework like the International Baccalaureate highly stimulating and professionally challenging."
There are different categories of international teacher. Some go into it at a young age because they want to see the world for a few years before settling down again in Britain. There are those who become career expatriates, moving from school to school and country to country while climbing the promotion ladder. And then there are some who don't set out to have a career in international schools, but are simply drawn to it.
In recent years, teaching abroad has become popular among older teachers who take early retirement and head for the sun in southern Europe. The European Council of International Schools (ECIS) says there is a solid core of career expats who have been in international teaching for 20 to 30 years and have travelled widely.
Peter Price, the council's executive officer, says: "If you look at the heads of various schools overseas, most of them have come through the international system and have been out of their own country for a considerable time."
Recent changes within the council seem to indicate that a career structure for international teachers is now on a sound footing. The membership organisation was founded in the mid-1960s and recruits staff for more than 436 international schools around the world. This summer, it split its recruitment function into a separate Council for International Schools, leaving ECIS to focus on offering professional training to its member schools. It offers a range of distance-learning courses.
So, are we witnessing the development of a well-defined career structure for overseas teachers?
"Yes, I think more and more so, yes," says Mr Price. "Now, with the internet, for the first time we can address professional development properly."
The education department at the University of Bath offers a range of courses, including postgraduate qualifications in international education.
It runs modular courses that are available throughout the world. And the International Baccalaureate Organisation (IBO), which encompasses some 1,500 schools worldwide - 18 per cent of them international schools - has developed its own training framework.
Teachers working with the baccalaureate must undergo initial and continuing training for its primary, middle years and diploma programmes. This includes in-school training, seminars, workshops and regional conferences.
The IBO also has a website that provides teachers with support materials and chat rooms to allow colleagues to share good practice.
"As the core of teachers working in the International Baccalaureate schemes become more experienced and have professional development needs, we are looking to support them in the best way we can," says Mark Waterson, its teacher education manager.
But it can be lonely at the top. Peter MacKenzie is principal of the International School of Tanganyika, a secondary school in Tanzania. There is only one other international school head in the country, and he is an eight-hour drive away. He finds that attending events such as the International Baccalaureate heads' conference are very useful for networking, although the cost is quite a drawback.
"The cost is significant and the time out of school is also a concern," he says. "If you are working in Central Europe and can reach these venues quickly and cheaply, then they are of obvious value. But once you are located 10 or 15 hours away and the air fare, hotel and registration will set the school back pound;2,000 or more, then you have to ration yourself to the most important."
Even so, in his 13-year career abroad, Mr Mackenzie has still had far more access to professional development than he ever did as a class teacher in a UK comprehensive.
On the other hand a career in international schools can be a one-way street. A 1997 study at the University of Bath found that heads in British schools tend not to understand international schools, and find the experience gained in them largely irrelevant. Too often, working overseas is seen as taking a break from teaching - similar to raising a family - Jand seen as a disadvantage as it disrupts what is regarded as the normal career pattern.
Lack of knowledge of the national curriculum, GCSEs and A-levels was found to be a disadvantage for teachers seeking work back in the UK; their experience of other systems such as the International Baccalaureate did not compensate.
Mr MacKenzie left Britain in 1990, expecting that the move would be for life. So, would he ever consider coming back ?
"I could foresee significant obstacles," he says. "I left the UK before the introduction of the national curriculum - I know nothing about it. Nor have I any experience of Ofsted. I suppose I could get a job as a history teacher, but would I be of any interest to a school looking for a head? I doubt it."