THIRTY years ago in South Africa a small group of us, mainly white, former students, dreamed that we could help topple the apartheid regime by blasting down electric pylons and radio masts. We called ourselves the African Resistance Movement. This was a world where the African National Congress and the Pan African Congress were banned and the Liberal Party, to which most of us belonged, was soon to be banned.

The ANC leadership had effectively been put away by the Rivonia trial and their armed struggle was underground. We respected them but wanted to play our part. I was recruited by Hugh Lewin, one of the leaders of ARM and a journalist. I owed a lot to Hugh. He got me my first job, as a sub-editor on the Natal Witness in Pietermaritzburg and later a position on the Golden City Post in Johannesburg.

At intervals of about three months we would be told a raid was in the offing. First we would reconnoitre the scene. We would choose remote pylons, usually ones at an angle in the line, so that they would be more likely to fall over after the explosion. I always did the driving; I was pretty junior and I was unskilled with explosives. I would drop Hugh Lewin and a woman member of the group off near the scene, they would place the bomb and I would pick them up again at an agreed time. We were never stopped.

I'm not sure how many times we did it; I can remember three. It was unreal; I just blanked everything out and did it. The bombs were always timed to go off in the middle of the night, and we had a fair failure rate. If it was reported the next day that power supplies were down you knew you had hit home, but we didn't bring the government down.

These were strange days. I reported the trial of Nelson Mandela in July 1964, walking in to court among the Special Branch. We knew that police were frenziedly trying to break us and other underground groups. Then, one morning, as I called into the Post offices on my way to a few days' holiday, Hugh told me that one of the leaders of the ARM, had been broken and was talking to the police; that one colleague had passed through on his way across to the safe haven of Swaziland; that Hugh expected the police later that morning; that he wanted me to go on holiday and act normally. He would tough out any interrogation.

I did what I was told. I hitch-hiked to a holiday in Pietermaritzburg. My one and only lift was in a bus with Cambridge University student dramatists on their way to perform in Pietermaritzburg. When the news of Hugh's arrest broke that evening, I had to play the innocent. I continued the role when I got back to Johannesburg. I took food parcels to the Special Branch headquarters where Hugh was being held.

Then, one day they didn't let me out. Hugh had broken. I was made to stand on one spot. It is a devilish torture for would-be heroes. You torture yourself. I stood for two days. On the evening of the second day, a bomb exploded on the Johannesburg railway station. The police told me that 20 people had been killed. It was not until months later that I learned that, in fact, only one person had been killed. The police went berserk. I was virtually ignored as they dragged people in. I saw Hugh Lewin. I saw John Harris [the teacher who was later hanged for his part in the Johannesburg bombing].

John Harris was charged with the bombing. He had been, I think, the last remaining member of our group at large. And he had been in possession of a cache of explosives. He and I had discussed various options for continuing resistance including a dramatic bombing. I think when I was arrested he lost all reason. His plea of not guilty by temporary insanity was not accepted by the court.

I became aware of these events under interrogation and in solitary confinement. I was shocked and horrified by the station bombing. I agreed to give evidence against Harris because he had so violated our code. I can't know whether I would have made a different decision had I been at liberty or if I had shared a cell with colleagues.

I told the police I would not testify against Hugh Lewin and the others. They ignored me and took me to court and pushed me up the stairs. I didn't have the strength of will to refuse. I am told I gave evidence like an automaton. I deeply regret giving evidence. My only mitigation is that I had been in solitary confinement for about three months. I saw the world through my captors' eyes. I even inquired about joining the police force.

I came to Britain in December 1964 with my mother. I got a job at the Western Daily Press in Bristol and, later, at the World Service news desk at Bush House. In about March I was approached by a very hostile woman from South Africa who asked me to sign an affidavit saying my evidence against John Harris was untrue. I first of all agreed and then I thought it through. Such a withdrawal, I thought then, and now know, would have been of no weight. I have since seen the transcript of the Harris appeal and my evidence was not cited once.

I want to make the following points:

I have never practised or condoned terrorism. The Tories are attempting to paint me as a terrorist. They knew of these events - as did many people in Exeter - well before the 1992 election. They didn't use this knowledge because they never thought me a threat to Sir John Hannam (the sitting MP). In fact, I got an 8.5 per cent swing and came within 3,000 of winning. They know that I will beat their new candidate.

The definition of terrorism is slippery, but those who know their history will agree, I think, that when Winston Churchill, as a civilian, captured and blew up a train during the Boer War, he came far closer to terrorism than I did in the blowing up of pylons in remote veldt.

The ultra-left and liberals of the ARM who say I am not fit to be a candidate are out of step with the letter and the spirit of the law in the new South Africa where there is a general amnesty on all political wrongdoing before independence. Nelson Mandela himself has said that the people who committed wrongs on both sides during the apartheid period should be covered by the amnesty.

The issue of betrayal is murky: Hugh Lewin betrayed me; I betrayed Hugh Lewin; neither of us was a free agent. He paid with a prison sentence so it doesn't lie in my mouth to accuse him.

The left/liberals are also playing the Tory game. If you ask yourself who gains from all of this, the finger points only to the Tories. My view is that they were well prepared for this revelation - which to the people of Exeter is old hat. It needed raising at national level and the Guardian and Tribune did the honours.

I am not personally ambitious but I have spent five years as the candidate for the Exeter seat, hoping to represent them in a Labour government. If local people said to me that I should stand down because I was impeding the election of a Labour government, I would do so.

So far, all I have had from the people of Exeter is affection and support. Strangers have stopped me in the street to demand that I resist the pressures and "make sure you win for us". Friends have rung and written.

Phone-ins and vox pops on local radio and newspapers appear to be running about 90 per cent in favour of me staying. One man rang up the local BBC and said, "What I like about John Lloyd is that he fights for his principles."

Many times I have fallen short, but I hope always to fight for the principles of fairness and freedom as I did long ago in South Africa.