What was it that caused Chinese President Jiang Zemin to lose his cool on Friday and lash out at journalists accompanying Hong Kong's chief executive, Mr Tung Chee-hwa, to Beijing?
Possibly it was an accumulation of irritations over Hong Kong in recent days.
First there was Mr John Cushnahan's report for the European Parliament raising questions about the territory's economic independence. That struck a nerve in both Hong Kong and Beijing.
Then there Mr Chris Patten's visit to Hong Kong as EU Foreign Affairs Commissioner. The former governor pronounced that democracy was still a long way off.
Or perhaps Mr Jiang's own Deputy Prime Minister, Mr Qian Qichen, irked him by appearing too obviously to endorse a second term for Mr Tung, a former shipping magnate who has run Hong Kong since 1996.
Any suggestion that Beijing was fixing the re-election of Mr Tung, whose popularity ratings are low, would confirm suspicions that Hong Kong has little say over who should lead the territory.
Mr Tung was selected by a Beijing-approved committee in 1996, and the next chief executive will be "elected" in similar fashion in 2002.
The detonator for Mr Jiang's explosion was a question from a Hong Kong cable TV reporter, who asked if the chief executive was the "Emperor's choice" for another five-year term. Enraged, the Chinese President rose from his chair and snapped: "You are very familiar with Western ways, but you are too young. "You go everywhere in the world to follow the big news, but the questions you ask are too simple - sometimes naive!"
Beijing's power of decision was important, he said. When he said he supported Mr Tung, "it's not because I've chosen him, but it must still be done according to Hong Kong's laws."
The tirade gave television viewers in Hong Kong a glimpse of a leader who regards challenging and unscripted questions as an impertinence. The reaction there was scathing.
"Jiang Zemin throws tantrum, loses stature," said the headline in the mass-circulation Apple Daily, which carried a cartoon of Jiang spouting fire on blackened and bewildered television crews. His "condescending manner shows the hollow-heartedness and arrogance of Chinese leaders", said the Hong Kong Economic Journal.
"The President does not explode without there being repercussions," warned the Hong Kong Mail.
Critics said the open backing for Mr Tung would discourage other contenders and make the next election meaningless.
The sight of President Jiang lecturing the media about how to do their job, and warning journalists, "if you make any error in your report, you will have to take the responsibility for it", revived fears in Hong Kong about the freedom of the press.
The reporters present at least showed no signs of being cowed; they kept questioning Mr Jiang as they were being admonished.
Their job was to tell the public what the government's policy was, whether the leaders liked their questions or not, said Ms Mak Yin-ting, chairwoman of the Hong Kong Journalists' Association.
The press in Hong Kong still enjoys a robust independence, although it had a warning shot fired across its bows in April when a Chinese official said it should not report separatist views on Taiwan.
This is recognised by Mr Patten, who told the European Parliament that despite some areas of concern, "Hong Kong remains a free society, one of the freest societies in Asia."
Mr Cushnahan, reporting on his fourth visit to post-handover Hong Kong, also concluded that the fundamentals of the one country-two systems arrangement "remain reasonably intact". But in his report, adopted almost unanimously by the parliament, the Munster MEP suggested there was unfair competition, due to a number of tycoons gaining an undue and dominant influence in commercial life and the stock market. He singled out the Li Ka-shing family as the subject of local criticism.
Reputed to be the most powerful person in Hong Kong, Mr Li Ka-shing (72), was granted exemptions by the Hong Kong stock exchange for the listing of his Internet company Tom.com, and his son won a major government contract without open tender. There were significant implications for EU businesses if these reports were true, Mr Cushnahan said.
The pro-Beijing media in Hong Kong have condemned his report, which according to the Sun was "in line with remarks made by the anti-China-HK democratic camp."
It said Mr Li's holdings amounted to only 15 per cent of Hong Kong's market total, and not up to a third, as Mr Cush nahan stated.
The Sing Tao complained that it reflected the concern of some British businessmen who were more sensitive to government favouritism now than in the past - to which Mr Cushnahan retorted last night from his home in Ireland: "That is nonsense, I'm Irish."
Mr Jiang's outburst, however, has had the effect of underlining the report's concerns, and adding to another round of debate which has begun on Hong Kong's role three years after coming under Beijing's sovereignty.