The basis for what later became the Sunningdale Agreement was already being formulated in Heath's mind even before the change of governments in Dublin in March 1973.
Prior to Bloody Sunday, Heath adopted a contemptuous attitude towards the Dublin Government on matters relating to Northern Ireland. He said the North was none of Dublin's business. He was decidedly curt with Jack Lynch on the telephone on the night of Bloody Sunday, but a year later things were very different.
On his first full day in office as Minister for Foreign Affairs, Garret FitzGerald had a secret meeting with Heath in Downing Street.
That morning the new Irish Government had forwarded a three-page memorandum on their thinking on power-sharing, the Council of Ireland, and security matters that were to be outlined in a British white paper to be published the following week.
Heath believed the way forward in Northern Ireland was by power-sharing, and he was prepared to insist on a consultative Council of Ireland to secure the support of the nationalist minority.
But nationalists leaders were also insisting on restructuring the Northern Ireland police force. "The RUC in its present form will never be acceptable to the minority," the Irish memorandum concluded.
Garret, who was accompanied by Hugh McCann, Secretary of the Department of Foreign Affairs, expressed regret that the memorandum could not have been presented earlier, as "the new Irish government had taken office only the previous evening", but McCann noted that FitzGerald "assured the Prime Minister that complete security was being maintained by the government in regard to the substance of last week's talks".
There had been a secret meeting the previous week, but there is no account of this in the Irish State papers. Yet there is evidence elsewhere that Liam Cosgrave and his future Tánaiste, Brendan Corish, had a secret meeting with Heath the week before they came to power.
"Corish and I saw Heath before we assumed office," Cosgrave is quoted as saying in Stephen Collins' book, The Cosgrave Legacy.
The British state papers contain a record of the meeting at which Heath expressed concern over the likely reaction in Northern Ireland to the forthcoming publication of the white paper.
"It was possible there would be a complete breakdown of normal life after the White Paper was published, with extensive industrial action by Protestant workers," Heath warned. But he stressed that his government were "prepared to face up this situation and press on with our proposals".
Before the Sunningdale Conference of December 1973, Cosgrave had two further meetings with Heath in London on July 2, and at Baldonnel on September 17. A distinctive feature on each occasion was the paucity of information in the press statements issued afterwards.
Both governments clearly feared a backlash in the North, especially in the unionist community. Thus Heath and Brian Faulkner, the unionist leader, were anxiously pressing for greater security co-operation.
John Hume was insisting on an all-Ireland police force within the Council of Ireland. On the eve of Cosgrave's visit to Downing Street on July 2, Garret FitzGerald pressed the Taoiseach to exploit the Northern desire for security co-operation.
"The common law enforcement system, involving an all-Ireland element, through joint judges, alignment of criminal law, trial of people for offences committed in other jurisdictions and/or joint policing, is worth talking about in general terms, without commitment," Garret wrote to Cosgrave on July 1, 1973.
"This is one area where the unionists could, perhaps, be persuaded to consider in their own interest with all-Ireland elements."
This was not just wishful thinking on Garret's part. He was in touch with people on both sides of the divide in the North.
Brian Faulkner privately indicated some weeks later that he was prepared to accept an all-Ireland dimension to policing.
He stunned Dermot Nally of the Taoiseach's Department and Seán Donlon of the Department of Foreign Affairs by suggesting privately to them that "perhaps moves could now be made in the context of the council to set up an all-Ireland Special Branch".
The British resisted this, and Heath pointed out that Dublin was not keen on the idea either. Could Faulkner or even Cosgrave have delivered?
Cosgrave's ability to deliver a united police force must be questioned in light of the topic becoming a heated political issue in the general election of November 1982, when Fianna Fáil railed against Garret FitzGerald's views on joint policing.
IN addition to seeking more co-operation on security matters at the Baldonnel meeting in September 1973, Heath asked Cosgrave for permission for British aircraft to overfly the border. "This would involved two to five sorties by a Canberra jet, flying at about 30,000 feet," the British explained.
"The photographs would be used by the British to distinguish places where wires had been laid across the border to detonate mines or bombs in Northern Ireland."
(In 1979 Jack Lynch would get into all kinds of trouble within Fianna Fáil after he secretly agreed with Margaret Thatcher's request to allow the British to overfly the Border.)
In September 1973, Heath believed that Paisley whom he described as "an extremely shrewd operator" had the potential to undermine talks on a Council of Ireland. He could be extremely disruptive by making reckless allegations. When they met recently, Heath said that Paisley had "produced a shoal of red herring".
He therefore sought to sideline Paisley by getting Cosgrave to put pressure on the SDLP to agree to power-sharing, so that an executive could be formed and take part in talks with the two governments to set up the Council of Ireland.
With the executive in place, it could speak for both communities in the North, and Paisley could be excluded, because he was refusing to take part in the executive.
Heath told Paisley on November 9 that he could "not have it both ways" refuse to take part in an executive and then have a say in running it.
The final stumbling block at Sunningdale was overcome when the Irish government dropped its insistence that the Council of Ireland contain a common court for trying terrorist offences.
On reflection Garret FitzGerald admitted that the removal of the republic's territorial claim on the North in Article 2 of the Constitution might have allayed unionist fears. But this would have required a referendum in the Republic, and the Irish ministers feared that the referendum might be defeated.
When this provision was included in the Good Friday Agreement, a quarter of century later, it was ratified by an overwhelming majority.
Heath showed that he was prepared to stand up to Paisley and the loyalist bully boys. He published the white paper in face of a revolt by loyalist workers, and he pressed ahead with power-sharing and the Council of Ireland, but our government lacked the guts to ask our people to stand up to the bully boys here.
An opportunity was lost in 1973. Over 30 years on, so much seems the same.