The transcript of the phone call between the the leaders on the evening of Bloody Sunday shows Mr Lynch trying to restrain his emotions while Mr Heath sounds cold, even disdainful.
Here are some extracts:
Mr Lynch: "Lynch here. I am sorry to ring you at this hour but you will probably have heard the unfortunate news about Derry this afternoon."
Mr Heath: "It is very bad news, yes."
Mr Lynch: "Very bad news, yes. And from reactions received around the country at the moment it looks as if a very serious point has now been reached and the situation could escalate beyond what any of us would anticipate at this stage.
I am told that, according to reports I received and checked on the spot, the British troops reacted rather beyond what a disciplined force might be expected to, and, as you know, there were 13 killed and as many again injured"
Mr Heath: "Well, now, as far as any accusations are concerned I obviously cannot accept that."
Mr Lynch: "I assure you I can understand your point of view."
Mr Heath: "I must also point out that this arose out of a march which was against the law, which was banned, you have always asked me to ban marches. Faulkner banned them last August and renewed the ban, as you know, for a year. Now this was done, and it is a policy which you have always urged, and we believe it was absolutely right for him to ban marches.
Now the people therefore who deliberately organised this march in circumstances which we all know in which the IRA were bound to intervene, carry a very heavy responsibility for any damage which ensued - a very heavy responsibility - and I hope that you would at least condemn the whole of that unequivocally and publicly."
Mr Lynch: "Well I am waiting to get further clarification of the situation, but"
Mr Heath: "So am I."
Mr Lynch: "Well now, there is no indication at all that the IRA intervened before shots were fired from the British side. Now again you can disagree with that but this is the information I have got, and"
Mr Heath: "I am not going to prejudge it."
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Mr Heath: "Well you know it is very difficult to accept a condemnation of Stormont for doing something which you yourself have requested, you have constantly requested. You spoke to me last summer that marches should be banned."
Mr Lynch: "Because I think these marches are provocative."
Mr Heath: "Well then, this was a provocative march today."
Mr Lynch: "But the fact is that"
Mr Heath: "And against the law."
Mr Lynch: "Well it was a peaceful march up to the point when"
Mr Heath: "It was against the law."
Mr Lynch: "Yes."
Mr Heath: "And it was provocative."
Mr Lynch: "Yes. Well I admitbut on the other hand"
Mr Heath: "Well I cannot therefore take this as a criticism of Stormont."
Mr Lynch: "On the other hand, well the fact is that the whole thing arises as a result of the Stormont regime. It arises as a result of the"
Mr Heath: "It arises as a result of the IRA trying to take over the country."
Mr Lynch: "Well, we have no intention of letting them do that".