Taoiseach Jack Lynch received a flood of hate mail from around the world after the IRA's brutal murder of Lord Mountbatten in 1979.
But as a wave of revulsion gathered pace, Mr Lynch refused to cancel a holiday in Portugal to deal with the crisis and instead dealt with the matter over the phone.
Newly released Irish state papers show some letter writers criticised Mr Lynch for his failure to return to Dublin immediately after the murders in Mullaghmore, Co Sligo.
The papers showed that Mr Lynch ran up a telephone bill of IR£58.94 at his Portuguese hotel while dealing with the Mountbatten-generated crisis.
Hit by shock waves created by the killing, the Irish embassy in London told the British Government: “It would be difficult to exaggerate the anti-Irish bitterness here.”
And worried tourist trade bosses initiated immediate consultations to assess the consequences of the affair for the industry, fearing the effects long be longer lasting than any previous terror strikes.