For decades, illegal immigration has been testing the emotion of Britons, whether it was through the flood of Vietnamese boat people heading for the then UK-controlled territory of Hong Kong, the plight of illegal Chinese immigrants picking cockles in northwest England, or the thousands of people risking all in Calais to get to Britain.

Britain gave shelter to thousands of Vietnamese migrants fleeing Vietnam after 1975, with little fanfare and no apparent disturbance to British culture, in itself a melange of various ethnic groups, from Vikings through to Normans, Celts, West Indians, Africans of various nationalities and Chinese, as well as other Asians all of whom blended in over the centuries, each bringing their own extra spice to the demographics of a country of whose empire it was once boasted "the sun never set".

Chinese integration into the British way of life came in various ways, with British links in Asia - Hong Kong, Canton (Guangdong), Singapore, Malaysia - giving work to ethnic Chinese aboard ships of both the Royal Navy and the Merchant Navy.

The appalling deaths of 58 illegal Chinese immigrants packed into the back of a container lorry in Dover served as a jarring wake-up call to the normally easygoing approach in Britain, as did the equally dreadful deaths by drowning in 2004 of 23 Chinese workers, mainly from Fujian province of China, as they worked in freezing conditions for minute wages to pick cockles.

That event triggered revelations that thousands of Chinese workers were employed at below subsistence wages in the catering and food processing industries in the UK. Many had been trucked in illegally, and others simply overstayed various visitor and student visas.

Government crackdowns and an improving economic situation in China have apparently led to a dramatic lowering of those numbers. And there was never British outrage at their presence here, just acceptance that they didn't cause trouble, and worked hard.

But the focus has now changed, with Britons watching aghast the television news footage of thousands of would be immigrants and possible asylum seekers fleeing by boat from North Africa, landing in Southern Europe and, if we can believe the reports, heading directly for the northern French port of Calais.

There have been brutal scenes of immigrants, many of Middle-Eastern and African descent, clashing with French police and tearing down barricades to try and get at trucks and freight trains that will carry them through the Channel Tunnel to Britain.

What do Britons make of all this?