UK Prime Minister Boris Johnson's firmness in defending his motherland's integrity was rather striking as he stressed Northern Ireland is part of "one great indivisible United Kingdom".

He uttered these words as French president Emmanuel Macron implied the relationship between Northern Ireland and the UK was different from that of Toulouse and France, something he soon corrected. Johnson's quick reprimand shows his strong sense of defending his country's integrity.

How much better it would be if Johnson held a similarly careful attitude towards China's integrity.

In January, Johnson announced, despite firm opposition from China, granting BNO passport holders a route of applying for UK citizenship. He even mentioned "profound ties of history and friendship" with Hong Kong Special Administrative Region as UK's former colony.

The same Johnson has also attacked the National Security Law in Hong Kong, while six of his predecessors urged him to list the "crisis on Hong Kong" high on their G7 agenda. No term is more appropriate than "double standards" to describe his deeds.

Maybe Johnson could learn something from Macron, who has voiced his support to the "one country, two systems" principle and corrected his statement about UK and Northern Ireland. He knows how to respect another country's integrity.

Another lesson from this little interlude at the G7 summit is the suffering of people without a good, integrated market. In Northern Ireland, for example, local people would find it difficult to buy sausages from other parts of the UK after June 30 because of their arrangements.

The situation is similar to Hong Kong, where people get over 95 percent of their gherkins and 92 percent of lettuce from the Chinese mainland at normal prices and even higher safety standards. Even over 70 percent of the local fresh water supply comes from neighboring Guangdong province, which persisted in ensuring abundant water supply during a major drought in 2009.

This demonstrates the goodwill of the mainland's people to Hong Kong compatriots, as well as the central leadership's care for them.

Time for the few "pro-independence activists" in Hong Kong to give up daydreaming, and for the majority of Hong Kong people to speak out against their delusions.