The British and US governments turned down separate proposals from Mr Charles Haughey and Mr Sean McBride offering bilateral defence arrangements, the former Taoiseach, Dr Garret FitzGerald, maintained last night.
Speaking at the Royal Irish Academy conference on "Small States and European Security", Dr FitzGerald said it was widely believed that Mr Haughey proposed Anglo-Irish co-operation on defence to Mrs Thatcher in December 1980.
This was denied at the time by Mr Haughey.
Dr FitzGerald said that such a proposal was ruled out by the British Prime Minister in March 1981 when Mrs Thatcher said that "if Ireland wished to discuss defence it would presumably do so with a much wider group of nations".
In 1950, he said, a proposal for an Irish/American defence pact was supported by Sean McBride as minister for external affairs, but was rejected by the US because it did not want to weaken NATO, and because of British opposition.
"It is interesting that these two approaches are associated with the two post-war politicians most identified in the public mind with traditional nationalist attitudes, viz. Mr Sean McBride and Mr Haughey."
He said Irish neutrality in its present form was largely the accidental and unintended product of events almost 50 years ago.
A myth of "traditional neutrality" had developed from the success of a pragmatic Irish decision to be a non-belligerent in the second World War, Dr FitzGerald maintained.
He said that Ireland's neutrality in the second World War represented an assertion of sovereignty by a new State.
It also reflected a fear of aerial bombardment, but more importantly a fear that voluntary involvement in the war on the Allied side would lead to a revival of the Civil War.
The success of that policy had led to the development of the concept that Ireland had a tradition of neutrality, he went on.
But while Ireland was a non-belligerent during the second World War, "it is at least questionable whether Ireland can properly be described as having been neutral, because the scale of assistance given secretly to Britain was scarcely compatible with the concept of neutrality under international law".
The co-operation had included making coastguards' reports available to Britain; providing an air corridor from Lough Erne to the Atlantic over Co Leitrim; agreement that the British navy could attack German submarines in Irish coastal waters; no ban on the enlistment of Irish people in the British forces, as was the case in other neutral states; close military intelligence co-operation; and various other matters.
Ireland's present stance on neutrality was confused, Dr FitzGerald went on.
"This confusion reflects a divided public opinion, an important section of which remains strongly influenced by a desire to be detached from anything that can be represented as involving a military commitment outside the compass of the United Nations."
The conference, the 19th annual conference of the Royal Irish Academy's National Committee for the Study of Foreign Affairs, is being held in association with the Finnish Institute in London.
It continues today and tomorrow.