This year he has returned to Hong Kong for his first extended stay since then, this time as a visiting professor at the Chinese University of Hong Kong (CUHK). There the Cambridge academic has been teaching Tang dynasty history to local undergraduates and pursuing his own studies of the eighth century poet Du Fu.

It is unusual in Hong Kong for western academics to teach a subject long regarded as the preserve of Chinese scholarly study.

'There is a kind of cultural prejudice which means Chinese people are sceptical about how much someone from outside their society can know about their past,' he said.

'But I believe scholarship is an international activity, despite the natural scepticism many Chinese have about the abilities of western scholars. The well trained western scholar can be as effective as their Chinese counterparts.'

Although students might be wary, many within Chinese academic circles did now concede that westerners teaching Chinese traditions could identify important issues and questions to feed into the academic agenda, he said.

American scholarship had, in particular, played a leading role in Chinese studies, he said. But Cambridge was looking to compete by increasing its strength in the field through the East Asia Institute focusing on China, Japan and Korea, that Professor McMullen directs.

What had caught his interest was the sophistication of Chinese culture and administrative traditions, he said. 'The Tang dynasty ran an empire of 50 million people at a time when Britain had a population of two to three million. It did so with remarkable success in ensuring internal stability and a reasonable standard of living for the agrarian population.

'The state was extremely sophisticated. It was also very well documented. It ran on paper in the eighth century - the sources are copious. It had a state education system, public exams - even in subjects like maths and criminal law - and the elite wrote poetry that is remarkable in its range of concerns.'

But despite Professor McMullen's personal academic interest, the East Asia Institute is increasing its focus on contemporary rather than ancient China. He sees its new MPhil Chinese Studies 'conversion course' as a significant channel for increasing China-related expertise in a range of careers.

The two-year course allows students from other disciplines, especially commercial law, economics, management studies and anthropology, to study the Chinese aspects of their subjects and learn the language. Two semesters are spent at Peking University in Beijing. The course relies on collaboration between different faculties and departments, with law, international relations, social anthropology, and the Judge Institute of Management Studies all involved.

'Our course is unique in that it combines professional language and discipline training and experience of living in a Chinese language environment,' he said.

Cambridge likes to play on the metaphor of the bridge in its name. 'It is important people are crossing the bridge in both directions. There should be fully trained western young scholars qualified in language and discipline crossing from Europe into China, as well as many coming in the other directions.'

The East Asia Institute was founded in 2000 as part of Cambridge's drive to give a higher profile to study of the region. It was also necessary to decouple East Asia from the 18th century concept of the Orient. 'The Orient has been defined as beginning in Casablanca and ending in Tokyo, which is ridiculous,' he said.

Like many senior academics, Professor McMullen finds himself increasingly involved in fund-raising. Government funding for the Chinese studies MPhil runs out next year but it has already received some expressions of interests to help cover its annual #300,000 (HK$4.2 million) running costs.

Funds shortages have resulted in controversial decisions to scrap Chinese studies at other British universities, notably Durham. But Professor McMullen is confident the field is secure at Cambridge. 'It is inconceivable that a major international university could possibly cut out Chinese studies. The endorsement of the new vice-chancellor [Alison Richard] is an indication that it has a good future.'

Professor McMullen is one of two visiting professors from Cambridge at CUHK, the Nobel Laureate economist Sir James Mirrlees being the other. Professor Billy So Kee-long, chairman of CUHK's history department, has made a return exchange to Cambridge.

'The links that have developed are within the particular interests of individuals. There is less likely to be firm institutional links,' he said.

During his stay, which ends next week, Professor McMullen has lectured on the traditions of political dissent during the Tang dynasty, dealing with the highly topical question of how permissible it was to criticise the political agenda. 'There was definitely a concept that high loyalty to the state might involve you in criticising it.'

This was also a theme in the writing he has been doing on Du Fu's attitude to the state, which has particular resonance in light of the debate over patriotism raging in Hong Kong and Beijing.

'Du Fu has been praised as a patriotic person, who venerated the symbolic aspects of emperorship. But at the same time he had reservations about how policy was conducted and the way the court behaved. On the one hand he believed in the permanence of dynasty, on the other hand he criticised the court and senior politicians.'

But Professor McMullen is reluctant to spell out what present poets or politicians can learn from this. 'As an academic I can't have a political position, though I do have my own views,' he said.

'In the case of China it is important for an institution like ours to keep open contact with all academic interests in China, Taiwan and Hong Kong. We don't want to be forced into a position where we endorse one over another.'