The files released by the National Achieve for the first time, show that British cabinet secretary Robert Armstrong reported to then Prime Minister Margaret Thatcher about the ongoing cooperation between the United Kingdom and Ireland on May 4, 1985, three months before the agreement was reached, according to the newspaper.
In light of the negotiations that were supposed to lead to an Anglo-Irish agreement, he asked the head of intelligence coordinator for Northern Ireland "to prepare an interdepartmental assessment of the present state of co-operation between the Irish and British authorities against terrorism", according to the newspaper.
Armstrong also noted that the flow of information "between the Intelligence and Security Branch of the Garda [Ireland's National Police Service] on the one hand and the Security Service and the MPSB [Metropolitan Police Special Branch] on the other" was of "crucial importance in the fight against terrorism in mainland Britain."
According to the newspaper, the UK security services assisted the Irish Garda in fighting against Arab terrorism and counter-espionage.
The Anglo-Irish conflict, also known as The Troubles, was one of the bloodiest counter-insurgencies fought in Europe since the end of the Second World War. It claimed 3,530 lives and injured a further 47,500 people.
