Irish sympathy after a helicopter crash killing senior UK military and policing intelligence figures showed how much security co-operation had improved, British officials said.
In June 1994 the Chinook crashed into a mountainside on the Mull of Kintyre in Scotland in thick fog, killing 29. Among the dead were senior Army, RUC and RAF officials.
Details were contained in a state file from the time released by the Public Record Office of Northern Ireland.
A UK Government official wrote: "A few years ago we could have expected an embarrassed silence from the Irish at such a disaster involving acknowledged members of the intelligence community.
"These public reactions illustrate the change in attitudes towards security co-operation."
Then Taoiseach Albert Reynolds said the crash was a "dreadful tragedy" for the families of the dead and those who worked in public service.
Tanaiste Dick Spring said it was a setback in the common task of protecting human life against violence.
Garda Commissioner Patrick Culligan said he was deeply saddened, knew many of those killed personally and valued their advice and co-operation in counteracting terrorism and crime at every level.
Passengers onboard the helicopter comprised 10 senior members of the RUC and nine Army staff officers of various ranks engaged in counter-terrorism activities, together with six civilian security specialists working in the NIO. Four RAF crew members also died. The flight was not unusual, in an aircraft with a long-established reputation for safety and widely used in Northern Ireland, briefing lines contained in the archived file said.
The aircraft was en route from one secure base to another. A weather radar was not thought essential, the document said.
A personal statement from then Prime Minister Sir John Major (right) in June 1994 said: "These officers and officials from the RUC, the Army, the RAF, the Northern Ireland Office and other departments were all in their different ways carrying out work of importance to Northern Ireland. As I know from meetings during my visits to the province, they made light of the risks in their daily lives.
"Their skill and determination had helped to save many lives in Northern Ireland."