If you want to understand this week's events in Zimbabwe, a little history might be helpful. For it demonstrates how the responsibility for what has happened in that country over the past two decades lies firmly with Robert Mugabe and the decisions he has made.

The past terrible few years raise questions about how President Mugabe came to power. Was the Lancaster House agreement - which brought an end to the civil war in Zimbabwe and allowed for the victory of Mugabe - a mistake? I am convinced that it was not.

When I became Margaret Thatcher's Foreign Secretary in 1979 the Rhodesia/Zimbabwe problem was near the top of my in-tray. It had bedevilled successive governments ever since Ian Smith unilaterally declared independence in 1965 and set up a white-minority government. It had soured Commonwealth relations and damaged our relationship with some of our closest allies. The election of 1979, under a constitution that gave disproportionate power to the whites, which brought Bishop Abel Muzorewa to power was not recognised as legitimate by any other country, except South Africa, because Joshua Nkomo and Mugabe, the main rebel opposition leaders, were not allowed to take part.

Towards the end of 1979, however, the situation had changed. Nkomo felt that time was not on his side. He wanted a settlement as soon as possible. The Muzorewa Government and the whites in Rhodesia were fighting a war against the rebels that was draining the economy and which could not be sustained for much longer. The South Africans, who were supporting the Muzorewa Government, were finding the burden too great. The frontline states surrounding Zimbabwe all had reasons for wanting a solution; Zambia was the host to Nkomo's army, an imposition which they wished to end.

However, there was one person who did not feel it necessary to press for a settlement - Robert Mugabe. He felt that his Zanu guerrilla group was winning the war and that he would become Zimbabwe's leader.

Despite this, it seemed that it was worthwhile to have at least one more try to settle the problems at a conference to be held in London. I did not think it likely at the time that the Lancaster House conference would succeed.

There were a number of difficulties to be solved. There was the constitution, the elections and perhaps the most difficult of all, the land question. There was no way in which the whites in Zimbabwe would be prepared to accept the compulsory purchase of their farms. What was agreed to in the end by all parties was that willing sellers should be paid a fair price for their land and that the British and Americans would be prepared to finance this.

As the conference was reaching its end, it became clear that, albeit reluctantly, Nkomo and the Muzorewa/Smith Government would be prepared to accept the agreement on the table. Zanu, the Mugabe party, was not prepared to do so. He thought that, since they were bound to win power, election or no, success would be theirs without an agreement.

Presidents Nyerere of Tanzania and Machel of Mozambique pressurised Mugabe to accept. Privately, President Nyerere made it plain to me that he would not accept the result of any post-settlement election unless Mugabe won it.

In the event, as was wholly predictable, Mugabe won the 1980 election easily. The prospect of a Mugabe Government was worrying, since he was known to be a Marxist and had made incendiary remarks about what would happen if he gained power. The quietly spoken Mugabe worried me: he was secretive, seemed not to need friends, mistrusted everyone. Devious and clever, he was an archetypal cold fish.

Christopher Soames, a man of great good sense and the Governor of Southern Rhodesia, developed a close working relationship with Mugabe. A big and friendly man, Soames was able to persuade Mugabe that an orderly transfer of power and a tolerant attitude towards those who had been his enemies would be the right way forward. Mugabe's Government started tolerably well. Having seen food shortages while in exile in Tanzania and Mozambique, he knew it would be counterproductive to seize the well-managed farms of the whites. Nonetheless, we were never certain which way Mugabe would jump; I just had a dreadful feeling that he would leap in the wrong direction. In the end, Mugabe has proven to be a textbook example of Acton's dictum about how power corrupts.

If there had been no agreement in 1979 the war would have continued, many more people would have been killed, and Mugabe would, in the end, have won both the war and the presidency. Economic devastation would have come much earlier. There can be no doubt that the election of Mugabe in 1980 reflected the majority opinion in Zimbabwe. For all that has followed we did the right thing, the only thing that could be done back then.

So much for history. Now the future beckons. It will take a long time to restore the prosperity which that beautiful country once enjoyed. Yet the people of Zimbabwe are resilient. It says a great deal for them that, despite threats and intimidation, the recent election seems to have overthrown the Zanu-PF majority in Parliament.

Strictly speaking, this is now no longer our business, but a great many of us will feel that we still owe the people of Zimbabwe, who have been through such desperate times, all the help we can give them. Although Mugabe tries to paint Britain as a colonial foe, we should feel no embarrassment for our role in Zimbabwe's recent past nor about doing all we can to assist its people today. And those of us who remember the country as it once was can only condemn the selfishness and folly of the man who has brought this about.

Lord Carrington was Foreign Secretary, 1979-82, and chaired the Lancaster House conference

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