Twenty years ago, as a fresh graduate, I flew to Hong Kong just a few months after the handover to begin my first job. I spent five very happy years working as a journalist there and never expected that 20 years later I would be refused the right to come back.

In the past three years I have become increasingly concerned about the erosion of Hong Kong’s freedoms and the rule of law, and the threats to the “one country, two systems” pledge. I have had the privilege of hosting, in London, Joshua Wong, Nathan Law and Anson Chan, and of working closely with Martin Lee – all heroes and friends of mine. I decided it was time for me visit Hong Kong again, simply to meet people and to listen and learn about the current situation. I had visited Hong Kong several times over the past 15 years, but had not been back in recent times.

My intention was to meet people privately. I had made discrete enquiries about whether or not it would be possible or desirable to visit Joshua, Nathan or Alex Chow in prison, but even inquiring about the possibility drew the attention of the Chinese authorities.

The first indication I had that there was a problem came last Friday, when I received a telephone call from a British MP whom I know well and respect greatly. He’d had calls from the Chinese embassy in London expressing concern that an attempt to visit these three student leaders would pose “a grave threat to Sino-British relations”. I asked him to reassure the embassy that I would not be attempting to visit any prisons. I also promised not to undertake any public engagements or media interviews while in Hong Kong, and to meet the embassy upon my return for a constructive discussion and to hear their perspectives. These offers were rebuffed and I received further threatening messages from the embassy, culminating in a warning that I would be denied entry.

It appears there was another factor too. I serve as deputy chair of the Conservative party’s human rights commission, a voluntary role, and I am on the Conservative candidates list. It appears that the Chinese authorities misunderstood my status and thought that I was an MP or a senior party or government official, and that my visit to Hong Kong would be in an official capacity. One could forgive them for that mistake, because in China a party member is a party member, come what may. Nevertheless I sought to reassure the embassy, via a third party, that I was not representing the party, and certainly not the government, and that my visit was a purely personal, private visit to meet old friends and new acquaintances in Hong Kong. Unfortunately that did not satisfy them either.

In consultation with others, I took the view that if I were to cave in to pressure from the embassy, sent through unofficial text messages via a third party, I would be doing exactly what I have criticized others of doing: kowtowing to China. My conscience would not allow me to do that. How could I look my activist friends in the eye if I caved at the first hurdle? I decided therefore that I had to put it to the test by going as planned to Hong Kong. If the Chinese were serious then they would have to refuse me entry publicly, exposing yet another example of the erosion of “one country, two systems”.

Regrettably, this is what occurred. When I landed in Hong Kong the immigration officer put my name into the computer, and evidently the computer said no. She called other officers over, they took me to a private room behind the counters, and I was asked to wait. After a little while a plain clothes official conducted an interview with me. I assured her that my visit was a private visit and that I had lived in Hong Kong for five years. A little later she told me I had been denied entry and would be put on plane back to Bangkok.

One country, two systems is supposed to mean Hong Kong people ruling Hong Kong. Yet it is overwhelmingly clear that the decision to deny me entry was not taken in Hong Kong, but by the Chinese regime. One country, two systems is supposed to mean the rule of law, yet a solicitor, Albert Ho,was not allowed to help me. One country, two systems is supposed to mean basic rights in Hong Kong – freedom of expression and association – yet my own freedom of expression and more importantly the freedom of expression and association of those I had hoped to meet has been curtailed.

This is not about me. It is about Hong Kong. And it is clear from this very stark, personal, first-hand and painful experience that if one country, two systems is not yet completely dead, it is dying rapidly, being rendered limb from limb with accelerating speed. The world, and especially the United Kingdom with its responsibilities under the Sino-British joint declaration, must wake up to this. I am no threat to Sino-British relations. But I believe the conduct of the Chinese regime, particularly in Hong Kong, is.