Those three years have seen the authority massively upgrade its facilities and procedures, introduce state-of-the-art on-screen marking centres and prepare for the impending change to the senior secondary school system.

'Things within this organisation have changed remarkably,' Dr Hill said. 'When I look back on the three years, the distance we have travelled is quite remarkable. When the will is there you can achieve things very quickly.'

In 2004, Dr Hill was welcomed to an exams authority suffering from a long-term lack of structural investment and struggling in the face of harsh criticism following a series of scandals, including an investigation by the Ombudsman into missing exams scripts.

'Their systems were antiquated,' Dr Hill said. 'They were highly manual, running on computers that should have been obsolete 20 years ago. They were error-prone because of all the manual intervention that was needed, and the workflows and the patterns of work were desperate. That was a consequence of years of under-investment in the authority.'

The exams authority is self-funded, its budget relying entirely on the examination fees charged to students. To maintain those fees at an affordable rate and avoid an economic barrier to less-well-off students, the authority cut corners to balance short-term budgets. 'We would be, I think, the only exams authority in the world that isn't government funded,' he said. 'It is strange.'

Updating required millions of dollars from the government, principally to fund the equipment required to scan millions of pages of exam papers and set up secure centralised marking facilities.

Dr Hill said this had been possible due to the key role the authority had to play in reforms of the senior secondary structure and the government's commitment to ensuring the new Hong Kong Diploma of Secondary Education, due to be sat for the first time in 2012, would be a success.

'There has been a very clear vision of what needed to be done in education and a will to make it happen. I think all the key sectors in the education community are behind this and I think parents are too. Basically it is about giving all young people that opportunity towards secondary education and a broader education all the way through. It is such a positive agenda, you can commit to that and you can really go flat out to make it happen.'

The on-screen marking centres, introduced for the English and Chinese language papers this year, had been a total success, he said. 'It was predicted that nobody would turn up to these centres. In fact we were over-subscribed. We were told that no one would come back. I think very few markers would go back to the traditional way of marking, even though people had to travel to the centres. It was all predicted that after an hour they wouldn't be able to do any more because they would get sore eyes. They stayed on and marked.

'As a result, the marking was finished more speedily than in the past. It was finished more accurately.'

The trouble with scripts going missing had been essentially eliminated, he said. Manual errors in adding up marks, which had been a major headache, had also become a thing of the past.

'In the past, 11 per cent of scripts had errors in them. Now it is zero per cent.

'We are the only exam system in the world to have a rigorous psychometric underpinning to our examinations scale, maintaining standards. Look at how they have maintained standards in the UK, then look at us and you will see how we stand.'

The changes at HKEAA reflect the upheavals in the schools sector on a wider scale - extensive curriculum reform at all levels, proficiency benchmarking for language teachers, school closures due to demographic change, school inspections and quality assessments and a host of other contentious topics.

Resistance to those changes led to a standoff between teaching factions and the government over what was perceived to be a top-down approach. Much resentment was directed at the leadership of former education secretary Arthur Li Kwok-cheung and former permanent secretary Fanny Law Fan Chiu-fun.

But Dr Hill said he believed it had been an essential process, and Professor Li and Mrs Law's strong-handed style had been necessary. 'My perception is that in Hong Kong there has been, in education, a long period of remarkable stability with little change. In fact, beyond stability, I'd say it was almost stagnation.

'Different periods of the change process will need different leaders. Fanny Law and Arthur Li were strong leaders whose role it was to shake people out of their complacency and move things along. In the process, their style may not have gone down well with some people, although with others it did. I think they often generated a kind of love-or-hate relationship. There are many, including me, who deeply respect what Fanny and Arthur sought to achieve.

'Now, we have got to a stage where the foundations of the reform are actually in place,' he said. 'We have a new education secretary who clearly has a different style but it is appropriate to the stage we are in.'

Reforms were beginning to bear fruit.

'It does depend which school you go into, but I see the evidence that the culture is shifting. It might be three, four or five years off being able to turn around and say 'We made it'. But the best schools are already there,' Dr Hill said.

'Hong Kong is definitely moving the exam culture; it has definitely broadened the base of assessments. We are assessing much more broadly than any other country within the Asia region. And it is also promoting the view of the whole person very clearly - it is part of the curriculum all the way through and we are seeing the results.'

It was 'sad' people tended to focus on the negative side of the system. 'I don't know how many times Hong Kong has to get in the highest rankings on Pisa and on Pirls to make the point,' he said. 'It has been doing this consistently and there is no question it is in the very top rank of nations when it comes to education systems. '

All education systems had their flaws. Different countries faced different issues.

'When you ask people about the system they will use different words,' he said. 'In Hong Kong they will tell you about the stress of working hard. In Australia they will tell you about the tedious boredom of being in school. In America they will tell you other things, they will often talk about bullying, they will talk about the issues of physical security. 'We would like to take off some of that stress, but we don't want to take it all off. A certain amount is positive. It's just we want to avoid the excessive stresses and the excessive focus on exam results.'

After a short Christmas break in his native Australia, Dr Hill will be packing up for the south of France - he and his wife have owned a home near Nice for the past eight years. 'But I will stay active in education,' he said. 'I have a book to write and will be coming back to Hong Kong from time to time as a senior adviser to the exams authority.'

Dr Hill said he would not leave office without some regrets. 'We were unable to communicate properly the advantages of [school-based assessment],' he said. 'SBA has been part of exams in a number of subjects in Hong Kong for 30 years. We thought it had been accepted. In science, we haven't had a single complaint.'

And there was one element of his own Hong Kong education that was lacking: 'I never managed to learn Cantonese.'