A suggestion to move the population of Hong Kong to Northern Ireland sparked a flurry of correspondence in Whitehall in 1983, newly released documents show.
The bizarre plan was revealed in files published by the National Archives.
The novel idea came from a lecturer who warned that the British colony's 5.5 million inhabitants would need a home when it was returned to China in 1997.
It sparked some debate among officials, with one saying there were "real advantages" in taking it seriously.
Prof Christie Davies, an expert in the sociology of morality, censorship and humour at the University of Reading, suggested a new "city state" could be created in Magilligan, between Coleraine and Londonderry.
The move could revitalise the stagnant Northern Ireland economy, he said.
When details of his idea first appeared in the Belfast News Letter in October 1983, they caught the eye of George Fergusson, a junior official in the Northern Ireland Office.
He sent a memorandum to David Snoxell, a colleague in the Republic of Ireland Department of the Foreign Office, saying: "At this stage we see real advantages in taking the proposal seriously."
Among the benefits, he suggested, was that it would help convince the unionist population that the government in Westminster was truly committed to retaining Northern Ireland in the UK.
Mr Snoxell's reply suggested the conversation was not entirely serious.
"My initial reaction... is that the proposal could be useful to the extent that the arrival of 5.5 million Chinese in Northern Ireland may induce the indigenous peoples to forsake their homeland for a future elsewhere," he wrote.
"We should not underestimate the danger of this taking the form of a mass exodus of boat refugees in the direction of South East Asia."
A second Foreign Office official commented: "My mind will be boggling for the rest of the day."
But Mr Snoxell, now retired, revealed the exchange "was a spoof between colleagues who had a sense of humour".
"You can see it wasn't intended seriously," he said.
"Sadly, it's impossible to make jokes like this any more, the Diplomatic Service has lost its sense of humour.
"I think that's a shame because it's through humour that you build relationships, with other departments, with other diplomats at home and abroad."
Other archives in the National Archives release reveal:
- Alarm among officials over a visit by Greek culture minister Melina Mercouri, who was determined to secure the return of the Elgin Marbles from the British Museum
- Fury at the Foreign Office after Prime Minister Margaret Thatcher insisted on placating the Saudi royal family who had complained about a BBC report that Iranian pilgrims to Mecca had been mistreated and imprisoned by Saudi authorities.