He returned to his mother in Cheltenham and went to Bible College in January 1856 but continued to spend every spare moment preaching and witnessing on street corners. After college he travelled England and was soon preaching to great crowds as an itinerant evangelist. He embarked on a three year preaching tour which took him half way round the world. In Wales at just one meeting 10,000 people responded to the call of repentance. In England and Scotland he preached in the pulpits of Whitefield, McCheyne and Haldane. Alongside C.H. Spurgeon and D.L. Moody, he was considered one of the greatest preachers of that generation.
In February 1858 he arrived in Dublin and preached to great crowds which included ministers and members of parliament. His pointed gospel statements were published on the front page of the city’s newspapers. Then in Belfast he preached to great crowds with dynamic effect. The following year (1859) he was back in Belfast preaching in the open-air to crowds of 20-30,000 people. That was the year of the great Ulster revival when 100,000 souls turned to Christ. During the ’60s they lived in Limerick where Henry caused riots when he preached on the streets and was once beaten half to death. In 1872, he started a missionary institute in Dublin with just six students. After three years he had over 100 students and moved to London. In the first 30 years of the Institute 1500 young people were trained and sent out to the foreign mission-field. He started several different mission societies, wrote a number of classic books and raised a family of children who served God faithfully.