Towards the end of his life, missionary Thomas Cochrane declared: 'All my prayers have been answered.' That is some claim, and when I first came across it, as a teenager, I was sceptical. Many years later I inherited Tom's papers, including his day books, and when I wrote his biography, Thomas Cochrane and the Dragon Throne, they helped me to understand how he could make that claim.

Born in Greenock, Scotland in 1866, Cochrane was converted at the age of eight and soon started to get up at dawn every day, to spend at least an hour on what he called 'knee drill.' He would pour out his heart, repenting of his boyish sins, pleading for grace, praying for his family and friends and lamenting the evil he saw around him. Soon he was begging God to give him 'the right person' so that he could save at least one soul a day. As he grew as an evangelist, so did the size of that request.

Then sudden tragedy struck. When he was 13 his father died, leaving Tom's mother a penniless widow with three children. Tom showed a degree of faith astonishing in one so young. He wrote: 'God has been pleased to take Father away before us. The Lord gives and the Lord takes away, blessed be the name of the Lord. We are not quite sure what we will do, but we will see.'

Suddenly his childhood and schooldays were over. Now he was working long hours for slender wages in an office by day and Greenock docks by night. For 10 years he was the family's wage earner, protecter and defender. Meanwhile he set his heart on becoming a medical missionary and every spare moment was taken up with studying. Yet he longed to spend more time with God. His prayers echoed that of Martin Luther: 'I have so much to do today, that I shall need to spend three hours in prayer.' Once trained, he asked the missionary society he had approached to send him to 'the neediest place on earth' – and they sent him to Mongolia. Life there was hard and dangerous: Westerners in general and missionaries in particular were often resented, if not actively opposed. Cochrane could have been killed on more than one occasion, and he faced the greatest danger during the Boxer Rebellion of 1900, when over 30,000 people were killed, including 300 missionaries. He and his family, and that of his co-worker, Rev James Liddell (father of the Olympic runner, Eric Liddell) escaped.

Prayer moulded Tom. The truth is that as a medical student and a missionary, he learned what many Christians never learn: not just to cry out in prayer, but to wait patiently for the answers to come. He spent as much time listening to God as in crying out to him; significantly he described this as 'my times of thunder', for it was then that he heard the voice of God speaking. His prayer habit was 'a perfect hour spent each day in the presence of God'.

His day books are frank about his failings and frustrations. He once wrote that the greatest challenge facing a Christian is to understand the meaning of the word holy and how to live a life that is set apart and pleasing to God. It was difficult for he was a man in a hurry and any delay was irksome. He had little time for colleagues who did not see things his way or dragged their heels. Men and women who accomplish great things for the Kingdom are often like that. They have an edginess that comes from strong convictions and a sense of urgency. I liken them to successful businessmen whose dynamism borders on the ruthless.

Nonetheless Tom grew into a man of great self-control, rarely raising his voice and firm but fair in his judgments. This proved of great value on the mission field. When he had to confront a Chinese person he did so in way that did not cause him or her to lose face. He learned the wisdom of the Chinese saying: 'If you are patient in one moment of anger, you will escape a hundred days of sorrow.'

When he conceived the idea of a western medical school in Peking, he had no money, influence or sympathisers. The society around him was ignorant of science and hostile towards the innovations of the 'foreign devils'. He prayed a simple prayer: 'Father God, help me to touch the Dragon Throne!' Working in obscurity amongst beggars in the city's slums, he prayed it every day for nearly five years. When the time was right, God answered it with an astonishing sequence of miraculous events.

The final event involved the dreaded Empress-Dowager Cixi, who was virulently anti-Christian; she had backed the Boxer rebels in 1900 and had the blood of thousands of Christians on her hands. Against all expectations, she not only gave permission for the school to be built, she donated 10,000 ounces of silver to fund it. Later Tom was granted an audience in the Summer Palace and became the only missionary to stand before her. Through God's grace, he did indeed touch the Dragon Throne.

I believe the reason that Tom Cochrane could say, without a hint of boastfulness, 'All my prayers have been answered,' lay in the fact that he listened intently for God's thunder before he committed himself to a word of petition. Prayer has been described as submitting the human spirit to God's Spirit and aligning our will to be in perfect agreement with his. It takes far more listening, self-humbling and patience than most of us possess, but if we succeed something wonderful happens. We pray only the prayers which the Holy Spirit approves, which the Son commends to the Father and which the Father is pleased to grant.

Andrew Adam's career has included being a medical officer in the RAF, journalism, pathology and male modelling. Since retiring from medicine, he has been a church elder, a police chaplain, a street pastor and a guest speaker on Cunard liners.

Thomas Cochrane and the Dragon Throne is published by SPCK.