Peter Tripp was the head of the Foreign Office's Near-East Department during the Black September crisis. He knew the ground well, having worked in Amman and shortly to take up a post as Ambassador to Libya.
BBC Television's UK Confidential programme spoke to him about the crisis - and the advice he gave to ministers as they decided the fate of Palestinian guerrilla Leila Khaled.
Here are the edited highlights of that interview and the full views of the British government, revealed in full for the first time in 30 years.
What was the atmosphere like before the crisis - did anyone see it coming?
We weren't aware that anything was going to go wrong but we were obviously very concerned about the situation in Jordan.
We had extremely close contact with the king and with his ministers and we were worried about the stability of the Jordanian regime.
We weren't really aware of how far the opposition, the PFLP, would push their enmity to the King.
In fact we had no idea that they could get quite so worked up as they did. So when the balloon went up and the hijacking took place, we had to move really quickly.
There were the usual calls for military intervention and we knew this would be useless.
We had to concentrate on the situation of the king and his government and how best to protect him and make sure that he sort of ran out of town.
So what happened when the hijackings took place?
Immediately we got the emergency unit set up and had tremendous co-operation from my various colleagues.
Telex Prem 15/202: Warnings of threats to life
We had to keep ministers closely informed. I always found [Foreign Secretary] Alec Douglas-Home was extremely approachable and very level-headed.
[Prime Minister] Edward Heath was very patient, very approachable and very level-headed.
If you named the problem, he'd sit and cogitate and then say ask you a couple of questions and then say yes, do that.
From my point of view very reassuring.
Why was Leila Khaled detained?
When we heard that Leila was on the plane in the UK, it was decided that she had to be detained.
We knew that various powers would be very interested in getting their hands on her.
We had to make sure that she was kept by us as safely as possible until her fate had been decided.
There was one school of thought that said, get rid of her as quickly as possible, send her out again.
That's easier said than done.
We couldn't commit her to prison because the Palestinians, the PFLP or Fatah, would consider that we were now going to keep forever.
We had to find some way of squaring the circle.
Communications arrived from Jordan warning of the threat to the hostages if Khaled was not released - what did you do next?
I told Mr Heath that the telegram we had from Amman was to the effect
that unless Leila Khaled were released within a matter of hours something really drastic would be done.
CAB 164/795 7/09: Cabinet weighed options
Well we had a fair idea of what the drastic something would be - the blowing
up of our hostages in an airplane.
He said that we must do it because we could not let 50 passengers be blown up just because of our obduracy.
We were authorised to let [Amman ambassador] John Phillips know this decision.
He could then let the PFLP know that Leila Khaled would be released in due course.
The announcement, confirming that Leila Khaled would be released in exchange for the hostages was issued to the media and broadcast by the BBC in Arabic to the Middle East.
What effect did the announcement have on the subsequent PFLP thinking and action?
We certainly didn't get the impression that they thought that we were going to
be a pushover on every occasion.
This was from our point of view a one-off and we hoped it would be the last one-off.
But didn't they get what they wanted?
They probably thought they were on the right track. But in the long-term they found they were on the wrong track.
King Hussein re-asserted his authority and the PFLP shut up.
We realised that we couldn't hold on and didn't want to hold on to Leila Khaled.
There was a price to be paid in letting her go, we would have to abandon or at least compromise our own principles.
But when the chips are down, do you sacrifice the lives of 40 or 50 passengers in an aircraft for one terrorist woman?
The answer in our book was, no you don't.
What about the position of King Hussein himself? What effect did this decision have on him?
I think that King Hussein would have been very surprised and perhaps shocked. We were doing something which he hadn't initiated, he hadn't agreed to.
But in the end I expect that he swallowed his pride and thought well, they hold all the cards.
I think he was quite enough of a pragmatist to know that you've got to do certain things and one of these was to negotiate with the enemy.
Wasn't he left in a situation where he was perhaps reliant on the Israelis?
I don't think that he put more faith in the United States or the Israelis than he did in the British Government.
CAB CONC 21/09: Hussein's appealed for aid
We had been his staunch supporters throughout the years and I very much doubt whether he would just have concluded that we were going to ditch him in favour of somebody else.
Our interests in the Arab world were extensive. We had to have regard to our own wider interests in dealing with King Hussein.
But that didn't mean to say that we had to throw him overboard at the first sign of trouble.
King Hussar's position looked shaky. But the Palestinians weren't working as one.
Our assessment was that you stuck with King Hussein who was going to be a better bet than the PFLP, Fatah and all the rest of them.
But were we stepping back from King Hussein?
King Hussein's relationships with other Arab countries were changing and you could not just nail your colours to that particular mast and say well we'll go down with the ship.
There's a certain amount of self-interest in all this.
The Arabs have a phrase saying do not leave your friend when he is in trouble and that's something which you always bear in mind in the Arab world.
Where did Yasser Arafat fit into this? Was he someone that people were prepared to do business with?
At the time it certainly seemed that Arafat was a force to be reckoned with. He had not achieved the notoriety that he has today.
He represented a very strong theme in Arab nationalism and it seemed to us to be at least prudent not to cut off all contact.
We didn't have many contacts with him but we had to consider that this might some day be a man we'd have to deal with.
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