Ex-Taoiseach Garrett FitzGerald pushed Margaret Thatcher for several different local police services in Northern Ireland - citing the example of Brussels having 46 different forces.
The Irish premier privately told his British counterpart during crunch talks leading to the Anglo-Irish Agreement that the region was not normal and could not be dealt with in normal ways.
Problem policing could not be resolved in Derry and Belfast by simply recruiting more Catholics to the RUC, he argued.
Turning to the Belgian capital, Mr FitzGerald said a Walloon police force could be accepted by the Walloon population and a Flemish force by the Flemish people.
"We must get away from what Peel thought or did in 1846," he warned her during talks at Chequers in November 1984.
Robert Peel, father of the modern Conservative Party, founded London's Metropolitan Police and was also known for reacting slowly to the Irish famine, accusing the Irish of a tendency towards exaggeration.
Demanding urgent police reforms, he said one fifth of Belfast had been expelled from their homes since the outbreak of the Troubles in the "greatest mass movement of population since the last War", secret notes of the meeting reveal.
"You simply could not leave these enclaves without normal policing," he said.
Mr FitzGerald said in the absence of a reorganisation of policing it would be left to the IRA to police nationalist areas.
Young people were growing up in areas with a tradition of violence and anarchy, he said, adding: "They had never known a normal society."
But Mrs Thatcher asked if he wanted to see "Republican enclaves" with their own separate police forces.
She said there could "be no freedom unless there was law".
The British Prime Minister repeatedly focused on the Northern Ireland crisis as a security problem during the crucial two hour summit.
What horrified her most was that many people in the region never had the chance of a normal life because of the "security situation".
"They objected to been (sic) frisked and searched," she said, according to official notes of the meeting, just declassified under the 30 year rule.
"She wondered, however, was this not simply a feature of the situation which people should accept."
She personally would be happy to be frisked and searched as it was evidence security forces were doing their job and questioned why Catholics "corralled into ghettoes" were "not glad" of the measures, the secret files reveal.
While she agreed "in principle" to a joint British-Irish security council to advise on policing, Mr FitzGerald said it would have to be part of an overall political package as a security deal alone would be seen as "as helping you along".
"If you concentrate on security alone you simply will not succeed," he told her.
But Mrs Thatcher insisted she simply did not understand that, adding: "If the rule of law was upheld then we could have succeeded."
What was being suggested in "nationalist enclaves" was the price of policing the border was power in Government for 40% of the population, she countered.
Asked by Mrs Thatcher about the future of the Republic, Mr FitzGerald said it could be as bad as the North unless they got the IRA "out of the way".
He also foresaw "Provisional Sinn Fein" emerging as the "legitimate voice of nationalist Ireland" if constitutional nationalism was seen to be getting nowhere.
If no progress is made "Sinn Fein will take over", the Taoiseach said.
Mrs Thatcher stressed that whatever emerged from their talks it should not be seen as a result of the Brighton hotel bombing the previous month, but neither should the attack deflect them from any agreed path.
The IRA attack killed on the Conservative Party conference killed five people and injured 31.