Margaret Thatcher threatened to scrap a visit to Ireland because it was being "unfriendly" about the Falklands War, newly declassified files reveal.
The then prime minister was also in no mood to meet with taoiseach Charles Haughey because of Ireland's plans to back calls for a ceasefire in the conflict off Argentina.
State documents show how Britain pressurised Ireland during one of the most critical stages of the war to abstain from a planned United Nations resolution calling for an end to military action.
They believed every vote was crucial and Ireland had let it be known it was in favour of a ceasefire and would likely vote in favour of it.
An unnamed Irish diplomat at the UN attending lunch with then Conservative Foreign Secretary Francis Pym sent a cable back to Dublin warning about the threats coming from London.
The deterioration in relations was particularly disappointing to Mrs Thatcher, who had accepted the "unique relationship" between the two countries, he told the Irish official. He told Dublin in a cable:
According to the files, just released into the National Archives under the 30-year-rule, Mr Pym asked Ireland to at least abstain from a UN vote on a Panama-Spain proposed resolution to the Falklands crisis, calling for an immediate ceasefire.
But the diplomat wrote:
At the lunch, the diplomat also had a conversation with Sir Antony Acland, then head of the British diplomatic service in his role as permanent under-secretary of the Foreign office. The Irish diplomat wrote to Dublin:
In the event, Britain vetoed the ceasefire resolution and two days later the Versailles summit supported the British position on the conflict.