A former British diplomat says a bizarre plan to relocate the entire population of Hong Kong to Northern Ireland was a joke between government officials.

David Snoxell says he's shocked that anyone took his exchange of letters with fellow diplomat George Fergusson seriously.

Snoxell says the exchange — revealed Friday in a release of 1983 documents by the National Archives — "relieved some of the tension" at a time when Northern Ireland was wracked by insecurity following hunger strikes by republican prisoners.

The idea also illustrated anxieties at the time about Hong Kong's future. Then-Prime Minister Margaret Thatcher had begun talks with China on the subject in 1982.

The letters showed the officials joking about resettling 5.5 million Hong Kong people in a newly built "city-state" between Coleraine and Londonderry.