Andrew Rosindell, a Conservative member of the British parliament's foreign affairs committee, was hoping the panel would meet the veterans during its visit to the city as part of its inquiry into Britain's relations with post-handover Hong Kong and the status of the joint declaration signed by London and Beijing 13 years before the handover. However, the plan came to nothing after the Chinese government barred the trip.

During the ensuing debate, the minister responsible for Hong Kong affairs, Hugo Swire, told MPs last December: "As a co-signatory, the United Kingdom has a legal interest and a moral obligation for the monitoring and implementation of that treaty."

The anger has not abated, with the committee last week criticising the British government for not issuing a diplomatic protest to China's ambassador.

"[Hong Kong's present political situation] may remind Britain of us, a group of people left behind here for so long. Won't they think of their moral duties regarding this forgotten group?" said Harry Wong Hi-kwong, the only applicant among the three who agreed to be interviewed.

Wong, 50, a former Royal Military Police corporal who now runs a trading company, said he did not think London had a role in the city's current affairs. "Hong Kong is now Chinese soil. Britain could not help us even during colonial times, why would it help Hongkongers now?"

Wong said he had no plans to emigrate even if his bid for citizenship was successful, but his concerns over the political situation fuelled a need to provide an exit option for his five-year-old daughter in the future.

Wong, who signed his name to the anti-Occupy petition, said he felt the protest movement's prolonged blockade of city roads had damaged the spirit of rule of law. "During British rule, we established a culture of self-discipline and respect for the law. Now we have regressed to the 1960s or 1970s," he added.

The campaign group says that the passport applications have been filed by Rosindell's office to test information provided by the UK government that it may be possible for the ex-servicemen to apply under provisions in its nationality laws. "We think the chances are high," said Wong.

Roger Ching Yuen-ki, 60, chairman of the HKOR Benevolent Association (formerly known as the British-Chinese Soldiers' Benevolent Association) and a member of the campaign team, was one of those granted British right of abode ahead of the handover and plans to retire to the UK. He doesn't see why he should enjoy this right, while his former colleagues don't.

He said: "It's the right time to act … Now [British politicians] are criticising China for treating Hongkongers badly. So what about how Britain is treating us?"

He added: "China's handling of the Occupy movement has upset Hongkongers … Many of our colleagues would like to ensure their children live in freedom. There is more freedom in the UK than in Hong Kong … except that they pay higher taxes there."

Ching continued: "I believe more of us will want to leave Hong Kong because of the present political situation."

In November, members of the campaign team handed a petition signed by 301 British-Hong Kong veterans to the Prime Minister's Downing Street office, but failed in a bid to trigger a parliamentary debate on the issue.