The British government was deeply concerned at the drift of the Protestant population from the west bank of the Foyle in Londonderry in the late 1970s, according to confidential files released this week.
The government feared Londonderry was becoming two cities separated by the Foyle
The files show the Protestant population feared "the spectre of the west bank being abandoned to the Republic" while a local development officer feared the historic city was becoming "alien to many citizens".
The issues dominated a meeting between William Ross, the Unionist MP for Derry and Bishop (now Lord) Robin Eames with Secretary of State Roy Mason at Stormont Castle on 7 November, 1978.
Mr Ross said the drift of Protestants across the Foyle had grown worse since the late 1960s. In 1967/68 there were 12,000 Protestant electors on the west bank of the Foyle and this was now down to 4,000.
The main causes, he went on, were the points system for housing "which worked against Protestants" and IRA violence.
Mr Ross's two suggestions were that something should be done about housing, though he recognised the political difficulty, and an RUC station should be re-sited closer to the Protestant Fountain estate.
Dr Eames said there would be a large Catholic majority west of the Bann in the next 10 to 15 years.
It was urgent Protestants west of the Foyle should feel wanted and reassured or they could turn to extremists.
Responding, the secretary of state said he could not promise anything but would look into the problem.
Mr Mason asked an NIO official, A E Huckle, to undertake a study "to see if the Protestant drift from the west bank could be halted".
Unionist MP William Ross raised the issue with the secretary of state
As a result, Mr Huckle visited Derry on 28 November, 1978 where he met Sam McIlwaine, a local development official.
Mr McIlwaine felt little could be done to arrest the situation. "It was not a case of trying to prevent a drift; the drift had already occurred and might actually be stabilising," he said.
Protestant families were moving away from Derry to Antrim and Coleraine while young Protestants preferred Queen's University in Belfast or British universities to the new University of Ulster "which was largely Catholic".
Mr McIlwaine saw little prospect of reversing a pre-existing trend: "The supposed threat was largely psychological and territorial and probably could only be removed, if at all, by psychological measures."
The report was presented to the head of the Northern Ireland Civil Service, Sir Robert Kidd who asked Ken Bloomfield of the Department of Commerce to undertake a detailed study.
The result was a blunt report to Mr Bloomfield by D C White, the Derry development officer, dated 11 January, 1979.
Secretary of State Roy Mason commissioned a study into it
Mr White said over the past 10 years there had been a constant movement of population from the "Donegal side of the Foyle" to the east bank and other parts of Northern Ireland.
The result was reflected in dwindling unionist representation and a "drastic fall" in the membership of the Protestant churches.
Turning to the causes of the shift, Mr White listed political fears, the pattern of violence and "the almost total abandonment of the west bank by RUC personnel".
The official doubted anything could be done to reverse the trend.
He felt shopping and infrastructural projects should be used to promote the idea of interdependence.
"The river should be a link and not a barrier," underlining the importance of the new Foyle Bridge, he said.
Another visit to the city was made by officials on 22 January 1979.
In a report, they stressed "the disastrous political and social effects of a 'two-city' situation developing" and favoured the concept of the Protestant Waterside "remaining what it traditionally had been, a suburb of Derry".