Hong Kong's incorporation into the People's Republic of China emphatically does not mean free movement between the former colony and its new sovereign state.
On the contrary, movement remains tightly controlled, with some 500 Hong Kong policemen and a great deal of sophisticated equipment deployed to keep the border secure against an influx of illegal immigrants from the Chinese mainland.
"This is one country, two systems in practice," says senior inspector Charles Parker, one of the officers responsible for border security, referring to the formula under which the former British colony has been reunited with China.
In theory, it provides for the preservation of Hong Kong's capitalist system, while China retains its allegedly socialist system.
But at the border, the slogan is more concrete: it means the preservation of a 10ft-high, 25-mile long fence topped with two rows of barbed wire. Sensors on the fence alert a central control room if anyone touches it. At night, the entire area basks in a harsh floodlit glare.
Exchanges between the police forces are cordial, yet, despite coming under a single sovereign state, the forces do not conduct joint operations, their officers are not allowed to directly contact their counterparts on the other side of the border and they never stray into each other's territory in pursuit of law breakers.
Equipped with the latest human detection technology and full backing from the Hong Kong and Chinese governments, the police are holding the line against the territory's ultimate nightmare: an invasion of poor and desperate Chinese mainlanders.
For its part the Chinese government is also keen to ensure that its people are not "corrupted" or "spiritually polluted" by Hong Kong.
The authorities therefore have a strong interest in keeping China's newest piece of real estate apart from the old properties.
On the Hong Kong side of the border, the last remnants of the territory's farming communities work the land. On the Chinese side, vast steel and glass skyscrapers crowd the new city of Shenzhen. It looks as though the Chinese side is the land of opportunity; but the thousands of desperate illegal immigrants clearly take another view.
Despite the high risks of detection and the likelihood of being detained after arrival, thousands of mainland Chinese still take a gamble and attempt to smuggle themselves into Hong Kong. Some are lured by the tremendous outpouring of propaganda about China's resumption of sovereignty over Hong Kong.
Yet they are far from welcome. They face heavy-duty border controls which were intensified during the period of the handover of power.
The land border crossing is mainly for the young and fit. Older and less agile would-be immigrants sometimes try to get in by attaching themselves to the undercarriages of the big trucks which rumble across the border at the rate of some 22,000 per day. Some are seriously injured as they fall from the vehicles.
Illegal immigrants are safer and more likely to succeed if they are smuggled in by sea and the so-called snake heads, who make a living by smuggling Chinese into Hong Kong, tend to prefer this method.
Of the 23,180 illegals who were apprehended for being in Hong Kong last year, less than a quarter were caught at the land border. The rest either escaped detection when they came in or must have arrived by sea. An unknown number escape the dragnet all together.
Yet, while mainland Chinese can only dream of coming to Hong Kong, as many as 200,000 people walk across the border at Lo Wu during weekends, while on weekdays as many as 140,000 make the crossing.
This legal traffic is largely one way, involving Hong Kong residents going to work in China, visiting their so called "second" families or just crossing to take advantage of the cheaper prices for more or less everything in China.
No wonder that the free movement of Hong Kong residents sparks resentment among mainlanders. Chinese citizens are not even allowed into the border town of Shenzhen without a permit.
Land of revolution
Canton was traditionally insulated from much revolutionary activity in China.
Neither the Taiping rebellion of 1850s, which devastated much of southern China, nor the Boxer uprisings at the turn of the century brought much more than ripples.
But for a short period from 1905, Canton was the centre of revolutionary activity in China. There were six attempted coups, all planned from Hong Kong, all of which failed.
The last revolutionary effort was in 1911. It was another failure, this time involving terrible bloodshed, and it effectively dampened Cantonese revolutionary efforts.