One summer holiday, when I was nine, all my sisters, who are older than me, were taken from our home near Cape Town on a trip to the Victoria Falls, and to see all the wonderful animals at the Kruger National Park.

It was decided I was too young to go, which made me feel very left out. I got sent instead to stay with a boy from school, called James Walker. We had always been friends at school, but in the holidays he turned out to be a most grotty child, and he threw rocks at me and bullied me, which must have been very awkward for his parents, who got rid of me as soon as they possibly could.

They drove hundreds of miles to take me to relatives who lived at a place called Commanche Sands. And they whispered in my cousin's ear when we arrived: 'He's dreadful, we can't put up with him any longer.' I heard them saying it.

Cousin Francis had a chicken farm. There were thousands of these lovely little furry chickens, but there is a huge mortality rate among young chicks; many of them get trampled, and they can be quite cruel to each other. Every morning I was made to help my cousin take out the casualties from the previous night. I had to reach in below the fence and put the dead chickens into a satchel, and then take them to the crematorium. I hated doing it: when they are dead, the fluff seems to go out of them, and they just look pathetic.

We would go out very early in the morning, cousin Francis carrying a kerosene lamp, as it would still be dark. I remember the bitter smell of kerosene, the eerie, dancing shadows the lamp threw out, the old Dutch house with lace everywhere, and the many dark corners. And then we went out into the old barn where there were two huge cart-horses, great 18-hand beasts, a brown one and a white one. There were 5dozens of spiders' webs in that barn, too, and they were enormous, they had dust in them, and hung down like swollen bellies, and the spiders were extremely scary to a little person.

One morning, I was excused chicken- burning duties, and treated to a tour of the farm. Even that turned out to be a horrible experience. The family's lovely cocker spaniel, Bartles, got bitten right in front of me by a bomslung or tree snake, and died in a very unpleasant way. The bomslung is a browny-green colour, long and thick, and evil-looking. It hides in a tree, coiled up along the lower branches, and then leaps on its victim, buries its fangs and sticks like grim death. I watched helplessly as the snake writhed and twisted in a frenzied, murderous attack, while the poor dog howled and screamed, until eventually, mercifully, it succumbed. I've been frightened of snakes ever since.

At the weekend, cousin Francis and his wife took me down to a place called Betty's Bay, a very beautiful beach on the coast. When we got there, they went off with their friends and left me on the towels they had spread on the sand. As I sat there, waiting for them to get back, I happened to notice a young couple a few yards away.

They were talking intimately to each other, laughing and joking, while the man put sunburn cream on his wife's back. Perhaps they were on their honeymoon. They seemed very much in love, quite oblivious to the rest of the world as they kissed and caressed, and I felt rather embarrassed.

The man eventually went out into the surf, and I watched him become a little speck as he went further and further out to sea. I began to worry about him before his wife did, and I watched her, asleep on the sand, to see when she would wake up and look for her husband.

Eventually, she got up, and I saw her alarm increasing as the enormous tragedy that had happened somehow became evident to her, although she did not yet know for sure - and she started screaming, over and over: 'He's drowned, he's drowned.'

Several hours later, people dragged a body out of the surf, and the young wife jumped on top of the corpse of her young husband. It was the first time I had witnessed human tragedy first hand, and seeing a dead body unsettled me. I got quite good at shutting the recurring images out of my mind, but I could remember the screams of the woman for a long time.

I was generally a good-natured, easy child, but when my family got back from their wonderful Victoria Falls holiday, they found me in a very unsettled way. My mother tried to find out what had happened, but I couldn't speak about it. A few days later, I broke down in tears, and told her everything.

That holiday made me frightened for the first time. The fear of pounding water and creepy crawly things has stayed with me ever since; whether on my expeditions, or at home, they are absolute anathema to me still.

Sir Ranulph Twisleton-Wykeham-Fiennes Bt has updated his autobiography, 'Living Dangerously', which is published this week by Macmillan.

(Photograph omitted)