These calmer voices are expressed not only in private conversations, but have even found their way into the editorial pages of leading publications such as the weekly Economic Observer and the bi-weekly Caijing.

Such public cracks in the 'consensus' against Japan would not have been tolerated five years ago, but the liberalisation of society has allowed those who disagree with the mainstream to speak out on the subject. Other issues, such as the question of Taiwan's independence or the fight for religious freedom in Tibet, are still off limits.

The dissenting voices call a boycott of Japanese products absurd and see a trade war as being against the interests of both countries, especially when China's future depends on a free system of world trade.

They also challenge the government's policy of confrontation with Tokyo, which may lead to a Japan that is hostile, suspicious and re-armed - exactly the opposite of what is in China's strategic interest.

Leading the pack is economics and finance magazine Caijing, which said in a mid-April editorial China should separate economics and politics.

'What happens if people hostile to China call for a boycott of our products? This is not a result we want to see or can accept,' it said.

It argued that a boycott of Japanese products was irrational, since China had become a manufacturing base for multinationals, including those from Japan. Therefore, 60 per cent of Japan's exports to China ended up in exports that went back out to the world, after creating jobs and income for Chinese workers and the nation as a whole.

The call for such protectionism is particularly absurd in China, a country that is heavily dependant on free trade, exports and foreign investment. Since global quotas were abolished at the end of last year, China has flooded the world with textiles, provoking a backlash from manufacturers in the US and Europe and the politicians who represent them. The country is vulnerable to trade retaliation.

Japanese companies employ 9.2 million Chinese, having invested US$23 billion over the past five years, including US$5.45 billion in 2004 - more than 40 per cent of total Japanese investment in Asia for the period.

Last year China exported US$73.51 billion of goods to Japan, a rise of 26 per cent over 2003, making Japan its largest market in Asia. China became Japan's biggest trading partner last year.

Such economic integration makes it increasingly hard to say what is a Japanese product. As the demonstrators walked in bright sunlight towards the Japanese consulate along Shanghai's Yenan Road, curious onlookers and officers of the secret police shot still and moving images, most of them using Japanese-brand cameras made in factories in China. Are they a Chinese or a Japanese product?

One target of the boycott was Asahi Beer, which was accused by the China Chain Store and Franchise Association on its website of supporting a right-wing school textbook. As a result, supermarkets in many cities removed its cans from their shelves and consumers refused to buy it.

The company strongly denied any connection with the textbook and issued a statement that included an apology for wartime atrocities. It has been active in the China market, acquiring four well-known brands - Beijing, Yantai, Hangzhou Xihu and Quanzhou in Fujian. So do these beers count as Japanese products?

The bravest editorial came in the Economic Observer on April 4, at the start of the protests when the official rhetoric was at its loudest.

'Our final objective is to prevent Japan becoming a security threat to China in the future,' it said. 'We should not use all our force to contain Japan - no, a Japan with a strong economy, a society that is stable and a country that pursues peaceful diplomacy and respects international order is much more beneficial to China than a Japan that is weak, closed and irrational. The question is how to realise this goal.'

It then took the rare step of explaining to its readers the factors that led to Japan's invasion of China - the refusal of the Allied powers after the first world war to accept Japan as an equal, followed by US immigration policies that excluded Japanese.

Japan realised the 'rules' of international politics applied only to white nations. The chaos among competing warlords in China gave the Japanese military the opportunity to establish itself and override the strong opposition of the civil ministries at home.

'The facts show that, at whatever time and whatever place, war is not inevitable,' the editorial said. 'The Japanese invasion of China was a result of many factors, direct and indirect, profound and accidental.'

The message of the editorial was that whether Japan would again become an expansionist military power was in the hands of its Asian neighbours and the UN, just as it was in the 1920s and 30s.

It would be good for Japan to play a greater role in international affairs and take a seat on the UN Security Council, provided that it could make a proper acknowledgment of its history, the editorial concluded.

These are not arguments you will hear from officials of the foreign ministry or the scholars who explain China's diplomatic policy.

One Chinese magazine, News Weekly, revealed a startling fact about the school textbook whose approval by Japan's Ministry of Education on April 5 was the spark that led to the protests.

It is in use in nine government and eight private schools in Japan, less than 0.1 per cent of the total, and is one of dozens of textbooks available for school principals to choose from.

'Chinese may believe that all our textbooks do not acknowledge Japan's invasion of China,' said Keiji Ide, a spokesman for Japan's embassy in Beijing. 'This is incorrect. They clearly explain the invasion, the Nanjing massacre, the Marco Polo bridge incident and the tragedy and losses which the Japanese military inflicted on countries in Asia.'

He said that, in reaction to the military censorship imposed during the war which left the public unaware of what was happening in China and elsewhere, the government lost the power to approve textbooks after 1945. These are written by private publishing houses and approved by a committee of scholars and experts appointed by the ministry of education.