As my 70th birthday approached, I decided to make a start on my bucket list and booked a two-week adventure volunteering at a Thai elephant sanctuary. I remembered a magical encounter years ago with an elephant in Kerala: at the end of the day, she had laid down to rest and let me clamber over her, scrubbing her clean with a coconut shell. Elephants are extraordinary creatures; I’m fascinated by their intelligence, empathy and strong family relationships. I had been sad to read about the abuse they suffer at the hands of the tourism industry in countries such as Thailand.

In preparation for my trip, I took up weight training and a high protein diet; there was hard work and extreme heat ahead, and I was determined not to succumb to creaky joints and fatigue. I even visited the elephant house at Whipsnade zoo; a keeper told me the tourist elephants were the ones to watch – years of maltreatment made them unpredictable and sometimes malevolent. Hardly surprising, I thought.

I flew to Bangkok then headed to a village on the coast. The sanctuary I’d chosen takes elephants and their mahouts (keepers and carers) off the streets and allows them to earn a living by working with conservationists and volunteers like myself, who pay for the experience. The close bond between mahouts and their animals can last a lifetime, so I was sad to see the spiked metal bullhooks used to control the elephants were still in use.

It was hot, wet and sticky yet I was excited and happy to be there. My designated elephant, Boonsri, and I were introduced and my tasks explained. She was an old girl with a sad air. Like the others, she had been made to perform tricks in the city, working day after day with little rest or refreshment. It pleased me that, for her final years, she would have a more natural habitat. That first day was exhilarating. I tried to gain the elephant’s trust, feeding her bananas and pineapple leaves, and riding on her back to the pastures where the herd grazed. Her mahout accompanied me, showing me how to use my feet to control her and teaching me the words to make her stop or move on. Finally, I hosed Boonsri to relieve her from the heat and cleaned up football-sized piles of dung.

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Day two followed the same pattern. But as we walked to the paddock at dusk, Boonsri began to sway her head violently. On the third stroke she hit me, trunk first, then with her massive head, striking me hard on my shoulder and knocking me over. Before I could register the danger, I felt a massive weight on my ribcage. Her enormous foot was not resting (as in a circus act), but pushing down, crushing my chest. It felt like a truck was driving over me. It can’t have lasted more than 10 seconds but my head was filled with terror and the conviction that my end had come.

I could hear shouting, the yells of the mahout, someone screaming – it might have been me. Slowly, I felt the pressure ease. As Boonsri lifted her leg, I rolled free and was dragged to safety. It took more than half an hour for me to regain the ability to speak. I burst into tears with the relief. The commotion continued and I could see the mahout beating the elephant. I protested so he took her out of sight. I was horrified, but have to admit it was probably his bullhook that had pulled her foot off me and saved my life.

I was taken to the hospital and x-rayed. I still couldn’t breathe without extreme pain, but my ribs were intact. The doctor said: “You are lucky. You have internal contusions, but she could have killed you in an instant.” He was right: four tonnes versus nine stone would have been no contest.

I was sent to my lodgings with a bag of painkillers – and a dilemma. Should I cut short the trip and sue for compensation? My conscience told me not to put the charity’s work in danger. It was clear the mahout and his family were incredibly distressed. We’d all had a lucky escape. I insisted that, in future, the mahouts should remain between the elephant and the volunteer at all times, and they agreed without question. I continued going to the compound every day, not to handle the elephants but to sketch them – from a distance. I returned home with a healthy respect for these awesome animals, and the Whipsnade handler’s warning ringing in my ears.

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